ha_partition.cc

/*
   Copyright (c) 2005, 2013, Oracle and/or its affiliates. All rights reserved.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; version 2 of the License.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA
*/

/*
  This handler was developed by Mikael Ronstrom for version 5.1 of MySQL.
  It is an abstraction layer on top of other handlers such as MyISAM,
  InnoDB, Federated, Berkeley DB and so forth. Partitioned tables can also
  be handled by a storage engine. The current example of this is NDB
  Cluster that has internally handled partitioning. This have benefits in
  that many loops needed in the partition handler can be avoided.

  Partitioning has an inherent feature which in some cases is positive and
  in some cases is negative. It splits the data into chunks. This makes
  the data more manageable, queries can easily be parallelised towards the
  parts and indexes are split such that there are less levels in the
  index trees. The inherent disadvantage is that to use a split index
  one has to scan all index parts which is ok for large queries but for
  small queries it can be a disadvantage.

  Partitioning lays the foundation for more manageable databases that are
  extremely large. It does also lay the foundation for more parallelism
  in the execution of queries. This functionality will grow with later
  versions of MySQL.

  You can enable it in your buld by doing the following during your build
  process:
  ./configure --with-partition

  The partition is setup to use table locks. It implements an partition "SHARE"
  that is inserted into a hash by table name. You can use this to store
  information of state that any partition handler object will be able to see
  if it is using the same table.

  Please read the object definition in ha_partition.h before reading the rest
  if this file.
*/

#include "sql_priv.h"
#include "sql_parse.h"                          // append_file_to_dir
#include "binlog.h"                             // mysql_bin_log

#ifdef WITH_PARTITION_STORAGE_ENGINE
#include "ha_partition.h"
#include "sql_table.h"                        // tablename_to_filename
#include "key.h"
#include "sql_plugin.h"
#include "sql_partition.h"
#include "sql_show.h"                        // append_identifier
#include "sql_admin.h"                       // SQL_ADMIN_MSG_TEXT_SIZE

#include "debug_sync.h"

using std::min;
using std::max;


/* First 4 bytes in the .par file is the number of 32-bit words in the file */
#define PAR_WORD_SIZE 4
/* offset to the .par file checksum */
#define PAR_CHECKSUM_OFFSET 4
/* offset to the total number of partitions */
#define PAR_NUM_PARTS_OFFSET 8
/* offset to the engines array */
#define PAR_ENGINES_OFFSET 12
#define PARTITION_ENABLED_TABLE_FLAGS (HA_FILE_BASED | \
                                       HA_REC_NOT_IN_SEQ | \
                                       HA_CAN_REPAIR)
#define PARTITION_DISABLED_TABLE_FLAGS (HA_CAN_GEOMETRY | \
                                        HA_CAN_FULLTEXT | \
                                        HA_DUPLICATE_POS | \
                                        HA_CAN_SQL_HANDLER | \
                                        HA_CAN_INSERT_DELAYED | \
                                        HA_READ_BEFORE_WRITE_REMOVAL)
static const char *ha_par_ext= ".par";

/****************************************************************************
                MODULE create/delete handler object
****************************************************************************/

static handler *partition_create_handler(handlerton *hton,
                                         TABLE_SHARE *share,
                                         MEM_ROOT *mem_root);
static uint partition_flags();
static uint alter_table_flags(uint flags);

#ifdef HAVE_PSI_INTERFACE
PSI_mutex_key key_partition_auto_inc_mutex;

static PSI_mutex_info all_partition_mutexes[]=
{
  { &key_partition_auto_inc_mutex, "Partition_share::auto_inc_mutex", 0}
};

static void init_partition_psi_keys(void)
{
  const char* category= "partition";
  int count;

  count= array_elements(all_partition_mutexes);
  mysql_mutex_register(category, all_partition_mutexes, count);
}
#endif /* HAVE_PSI_INTERFACE */

static int partition_initialize(void *p)
{

  handlerton *partition_hton;
  partition_hton= (handlerton *)p;

  partition_hton->state= SHOW_OPTION_YES;
  partition_hton->db_type= DB_TYPE_PARTITION_DB;
  partition_hton->create= partition_create_handler;
  partition_hton->partition_flags= partition_flags;
  partition_hton->alter_table_flags= alter_table_flags;
  partition_hton->flags= HTON_NOT_USER_SELECTABLE |
                         HTON_HIDDEN |
                         HTON_TEMPORARY_NOT_SUPPORTED;
#ifdef HAVE_PSI_INTERFACE
  init_partition_psi_keys();
#endif
  return 0;
}


bool Partition_share::init(uint num_parts)
{
  DBUG_ENTER("Partition_share::init");
  mysql_mutex_init(key_partition_auto_inc_mutex,
                   &auto_inc_mutex,
                   MY_MUTEX_INIT_FAST);
  auto_inc_initialized= false;
  partition_name_hash_initialized= false;
  next_auto_inc_val= 0;
  partitions_share_refs= new Parts_share_refs;
  if (!partitions_share_refs)
    DBUG_RETURN(true);
  if (partitions_share_refs->init(num_parts))
  {
    delete partitions_share_refs;
    DBUG_RETURN(true);
  }
  DBUG_RETURN(false);
}


/*
  Create new partition handler

  SYNOPSIS
    partition_create_handler()
    table                       Table object

  RETURN VALUE
    New partition object
*/

static handler *partition_create_handler(handlerton *hton, 
                                         TABLE_SHARE *share,
                                         MEM_ROOT *mem_root)
{
  ha_partition *file= new (mem_root) ha_partition(hton, share);
  if (file && file->initialize_partition(mem_root))
  {
    delete file;
    file= 0;
  }
  return file;
}

/*
  HA_CAN_PARTITION:
  Used by storage engines that can handle partitioning without this
  partition handler
  (Partition, NDB)

  HA_CAN_UPDATE_PARTITION_KEY:
  Set if the handler can update fields that are part of the partition
  function.

  HA_CAN_PARTITION_UNIQUE:
  Set if the handler can handle unique indexes where the fields of the
  unique key are not part of the fields of the partition function. Thus
  a unique key can be set on all fields.

  HA_USE_AUTO_PARTITION
  Set if the handler sets all tables to be partitioned by default.
*/

static uint partition_flags()
{
  return HA_CAN_PARTITION;
}

static uint alter_table_flags(uint flags __attribute__((unused)))
{
  return (HA_PARTITION_FUNCTION_SUPPORTED |
          HA_FAST_CHANGE_PARTITION);
}

const uint32 ha_partition::NO_CURRENT_PART_ID= NOT_A_PARTITION_ID;

/*
  Constructor method

  SYNOPSIS
    ha_partition()
    table                       Table object

  RETURN VALUE
    NONE
*/

ha_partition::ha_partition(handlerton *hton, TABLE_SHARE *share)
  :handler(hton, share)
{
  DBUG_ENTER("ha_partition::ha_partition(table)");
  init_handler_variables();
  DBUG_VOID_RETURN;
}


/*
  Constructor method

  SYNOPSIS
    ha_partition()
    part_info                       Partition info

  RETURN VALUE
    NONE
*/

ha_partition::ha_partition(handlerton *hton, partition_info *part_info)
  :handler(hton, NULL)
{
  DBUG_ENTER("ha_partition::ha_partition(part_info)");
  DBUG_ASSERT(part_info);
  init_handler_variables();
  m_part_info= part_info;
  m_create_handler= TRUE;
  m_is_sub_partitioned= m_part_info->is_sub_partitioned();
  DBUG_VOID_RETURN;
}

ha_partition::ha_partition(handlerton *hton, TABLE_SHARE *share,
                           partition_info *part_info_arg,
                           ha_partition *clone_arg,
                           MEM_ROOT *clone_mem_root_arg)
  :handler(hton, share)
{
  DBUG_ENTER("ha_partition::ha_partition(clone)");
  init_handler_variables();
  m_part_info= part_info_arg;
  m_create_handler= TRUE;
  m_is_sub_partitioned= m_part_info->is_sub_partitioned();
  m_is_clone_of= clone_arg;
  m_clone_mem_root= clone_mem_root_arg;
  part_share= clone_arg->part_share;
  m_tot_parts= clone_arg->m_tot_parts;
  m_pkey_is_clustered= clone_arg->primary_key_is_clustered();
  DBUG_VOID_RETURN;
}

/*
  Initialize handler object

  SYNOPSIS
    init_handler_variables()

  RETURN VALUE
    NONE
*/

void ha_partition::init_handler_variables()
{
  active_index= MAX_KEY;
  m_mode= 0;
  m_open_test_lock= 0;
  m_file_buffer= NULL;
  m_name_buffer_ptr= NULL;
  m_engine_array= NULL;
  m_file= NULL;
  m_file_tot_parts= 0;
  m_reorged_file= NULL;
  m_new_file= NULL;
  m_reorged_parts= 0;
  m_added_file= NULL;
  m_tot_parts= 0;
  m_pkey_is_clustered= 0;
  m_part_spec.start_part= NO_CURRENT_PART_ID;
  m_scan_value= 2;
  m_ref_length= 0;
  m_part_spec.end_part= NO_CURRENT_PART_ID;
  m_index_scan_type= partition_no_index_scan;
  m_start_key.key= NULL;
  m_start_key.length= 0;
  m_myisam= FALSE;
  m_innodb= FALSE;
  m_extra_cache= FALSE;
  m_extra_cache_size= 0;
  m_extra_prepare_for_update= FALSE;
  m_extra_cache_part_id= NO_CURRENT_PART_ID;
  m_handler_status= handler_not_initialized;
  m_low_byte_first= 1;
  m_part_field_array= NULL;
  m_ordered_rec_buffer= NULL;
  m_top_entry= NO_CURRENT_PART_ID;
  m_rec_length= 0;
  m_last_part= 0;
  m_rec0= 0;
  m_err_rec= NULL;
  m_curr_key_info[0]= NULL;
  m_curr_key_info[1]= NULL;
  m_part_func_monotonicity_info= NON_MONOTONIC;
  auto_increment_lock= FALSE;
  auto_increment_safe_stmt_log_lock= FALSE;
  /*
    this allows blackhole to work properly
  */
  m_num_locks= 0;
  m_part_info= NULL;
  m_create_handler= FALSE;
  m_is_sub_partitioned= 0;
  m_is_clone_of= NULL;
  m_clone_mem_root= NULL;
  part_share= NULL;
  m_new_partitions_share_refs.empty();
  m_part_ids_sorted_by_num_of_records= NULL;

#ifdef DONT_HAVE_TO_BE_INITALIZED
  m_start_key.flag= 0;
  m_ordered= TRUE;
#endif
}


const char *ha_partition::table_type() const
{ 
  // we can do this since we only support a single engine type
  return m_file[0]->table_type(); 
}


/*
  Destructor method

  SYNOPSIS
    ~ha_partition()

  RETURN VALUE
    NONE
*/

ha_partition::~ha_partition()
{
  DBUG_ENTER("ha_partition::~ha_partition()");
  if (m_new_partitions_share_refs.elements)
    m_new_partitions_share_refs.delete_elements();
  if (m_file != NULL)
  {
    uint i;
    for (i= 0; i < m_tot_parts; i++)
      delete m_file[i];
  }
  destroy_record_priority_queue();
  my_free(m_part_ids_sorted_by_num_of_records);

  clear_handler_file();
  DBUG_VOID_RETURN;
}


/*
  Initialize partition handler object

  SYNOPSIS
    initialize_partition()
    mem_root                    Allocate memory through this

  RETURN VALUE
    1                         Error
    0                         Success

  DESCRIPTION

  The partition handler is only a layer on top of other engines. Thus it
  can't really perform anything without the underlying handlers. Thus we
  add this method as part of the allocation of a handler object.

  1) Allocation of underlying handlers
     If we have access to the partition info we will allocate one handler
     instance for each partition.
  2) Allocation without partition info
     The cases where we don't have access to this information is when called
     in preparation for delete_table and rename_table and in that case we
     only need to set HA_FILE_BASED. In that case we will use the .par file
     that contains information about the partitions and their engines and
     the names of each partition.
  3) Table flags initialisation
     We need also to set table flags for the partition handler. This is not
     static since it depends on what storage engines are used as underlying
     handlers.
     The table flags is set in this routine to simulate the behaviour of a
     normal storage engine
     The flag HA_FILE_BASED will be set independent of the underlying handlers
  4) Index flags initialisation
     When knowledge exists on the indexes it is also possible to initialize the
     index flags. Again the index flags must be initialized by using the under-
     lying handlers since this is storage engine dependent.
     The flag HA_READ_ORDER will be reset for the time being to indicate no
     ordered output is available from partition handler indexes. Later a merge
     sort will be performed using the underlying handlers.
  5) primary_key_is_clustered, has_transactions and low_byte_first is
     calculated here.

*/

bool ha_partition::initialize_partition(MEM_ROOT *mem_root)
{
  handler **file_array, *file;
  ulonglong check_table_flags;
  DBUG_ENTER("ha_partition::initialize_partition");

  if (m_create_handler)
  {
    m_tot_parts= m_part_info->get_tot_partitions();
    DBUG_ASSERT(m_tot_parts > 0);
    if (new_handlers_from_part_info(mem_root))
      DBUG_RETURN(1);
  }
  else if (!table_share || !table_share->normalized_path.str)
  {
    /*
      Called with dummy table share (delete, rename and alter table).
      Don't need to set-up anything.
    */
    DBUG_RETURN(0);
  }
  else if (get_from_handler_file(table_share->normalized_path.str,
                                 mem_root, false))
  {
    my_error(ER_FAILED_READ_FROM_PAR_FILE, MYF(0));
    DBUG_RETURN(1);
  }
  /*
    We create all underlying table handlers here. We do it in this special
    method to be able to report allocation errors.

    Set up low_byte_first, primary_key_is_clustered and
    has_transactions since they are called often in all kinds of places,
    other parameters are calculated on demand.
    Verify that all partitions have the same table_flags.
  */
  check_table_flags= m_file[0]->ha_table_flags();
  m_low_byte_first= m_file[0]->low_byte_first();
  m_pkey_is_clustered= TRUE;
  file_array= m_file;
  do
  {
    file= *file_array;
    if (m_low_byte_first != file->low_byte_first())
    {
      // Cannot have handlers with different endian
      my_error(ER_MIX_HANDLER_ERROR, MYF(0));
      DBUG_RETURN(1);
    }
    if (!file->primary_key_is_clustered())
      m_pkey_is_clustered= FALSE;
    if (check_table_flags != file->ha_table_flags())
    {
      my_error(ER_MIX_HANDLER_ERROR, MYF(0));
      DBUG_RETURN(1);
    }
  } while (*(++file_array));
  m_handler_status= handler_initialized;
  DBUG_RETURN(0);
}

/****************************************************************************
                MODULE meta data changes
****************************************************************************/
/*
  Delete a table

  SYNOPSIS
    delete_table()
    name                    Full path of table name

  RETURN VALUE
    >0                        Error
    0                         Success

  DESCRIPTION
    Used to delete a table. By the time delete_table() has been called all
    opened references to this table will have been closed (and your globally
    shared references released. The variable name will just be the name of
    the table. You will need to remove any files you have created at this
    point.

    If you do not implement this, the default delete_table() is called from
    handler.cc and it will delete all files with the file extentions returned
    by bas_ext().

    Called from handler.cc by delete_table and  ha_create_table(). Only used
    during create if the table_flag HA_DROP_BEFORE_CREATE was specified for
    the storage engine.
*/

int ha_partition::delete_table(const char *name)
{
  DBUG_ENTER("ha_partition::delete_table");

  DBUG_RETURN(del_ren_table(name, NULL));
}


/*
  Rename a table

  SYNOPSIS
    rename_table()
    from                      Full path of old table name
    to                        Full path of new table name

  RETURN VALUE
    >0                        Error
    0                         Success

  DESCRIPTION
    Renames a table from one name to another from alter table call.

    If you do not implement this, the default rename_table() is called from
    handler.cc and it will rename all files with the file extentions returned
    by bas_ext().

    Called from sql_table.cc by mysql_rename_table().
*/

int ha_partition::rename_table(const char *from, const char *to)
{
  DBUG_ENTER("ha_partition::rename_table");

  DBUG_RETURN(del_ren_table(from, to));
}


/*
  Create the handler file (.par-file)

  SYNOPSIS
    create_handler_files()
    name                              Full path of table name
    create_info                       Create info generated for CREATE TABLE

  RETURN VALUE
    >0                        Error
    0                         Success

  DESCRIPTION
    create_handler_files is called to create any handler specific files
    before opening the file with openfrm to later call ::create on the
    file object.
    In the partition handler this is used to store the names of partitions
    and types of engines in the partitions.
*/

int ha_partition::create_handler_files(const char *path,
                                       const char *old_path,
                                       int action_flag,
                                       HA_CREATE_INFO *create_info)
{
  DBUG_ENTER("ha_partition::create_handler_files()");

  /*
    We need to update total number of parts since we might write the handler
    file as part of a partition management command
  */
  if (action_flag == CHF_DELETE_FLAG ||
      action_flag == CHF_RENAME_FLAG)
  {
    char name[FN_REFLEN];
    char old_name[FN_REFLEN];

    strxmov(name, path, ha_par_ext, NullS);
    strxmov(old_name, old_path, ha_par_ext, NullS);
    if ((action_flag == CHF_DELETE_FLAG &&
         mysql_file_delete(key_file_partition, name, MYF(MY_WME))) ||
        (action_flag == CHF_RENAME_FLAG &&
         mysql_file_rename(key_file_partition, old_name, name, MYF(MY_WME))))
    {
      DBUG_RETURN(TRUE);
    }
  }
  else if (action_flag == CHF_CREATE_FLAG)
  {
    if (create_handler_file(path))
    {
      my_error(ER_CANT_CREATE_HANDLER_FILE, MYF(0));
      DBUG_RETURN(1);
    }
  }
  DBUG_RETURN(0);
}


/*
  Create a partitioned table

  SYNOPSIS
    create()
    name                              Full path of table name
    table_arg                         Table object
    create_info                       Create info generated for CREATE TABLE

  RETURN VALUE
    >0                        Error
    0                         Success

  DESCRIPTION
    create() is called to create a table. The variable name will have the name
    of the table. When create() is called you do not need to worry about
    opening the table. Also, the FRM file will have already been created so
    adjusting create_info will not do you any good. You can overwrite the frm
    file at this point if you wish to change the table definition, but there
    are no methods currently provided for doing that.

    Called from handler.cc by ha_create_table().
*/

int ha_partition::create(const char *name, TABLE *table_arg,
                         HA_CREATE_INFO *create_info)
{
  int error;
  char name_buff[FN_REFLEN], name_lc_buff[FN_REFLEN];
  char *name_buffer_ptr;
  const char *path;
  uint i;
  List_iterator_fast <partition_element> part_it(m_part_info->partitions);
  partition_element *part_elem;
  handler **file, **abort_file;
  DBUG_ENTER("ha_partition::create");

  DBUG_ASSERT(*fn_rext((char*)name) == '\0');

  /* Not allowed to create temporary partitioned tables */
  if (create_info && create_info->options & HA_LEX_CREATE_TMP_TABLE)
  {
    my_error(ER_PARTITION_NO_TEMPORARY, MYF(0));
    DBUG_RETURN(TRUE);
  }

  if (get_from_handler_file(name, ha_thd()->mem_root, false))
    DBUG_RETURN(TRUE);
  DBUG_ASSERT(m_file_buffer);
  DBUG_PRINT("enter", ("name: (%s)", name));
  name_buffer_ptr= m_name_buffer_ptr;
  file= m_file;
  /*
    Since ha_partition has HA_FILE_BASED, it must alter underlying table names
    if they do not have HA_FILE_BASED and lower_case_table_names == 2.
    See Bug#37402, for Mac OS X.
    The appended #P#<partname>[#SP#<subpartname>] will remain in current case.
    Using the first partitions handler, since mixing handlers is not allowed.
  */
  path= get_canonical_filename(*file, name, name_lc_buff);
  for (i= 0; i < m_part_info->num_parts; i++)
  {
    part_elem= part_it++;
    if (m_is_sub_partitioned)
    {
      uint j;
      List_iterator_fast <partition_element> sub_it(part_elem->subpartitions);
      for (j= 0; j < m_part_info->num_subparts; j++)
      {
        part_elem= sub_it++;
        create_partition_name(name_buff, path, name_buffer_ptr,
                              NORMAL_PART_NAME, FALSE);
        if ((error= set_up_table_before_create(table_arg, name_buff,
                                               create_info, part_elem)) ||
            ((error= (*file)->ha_create(name_buff, table_arg, create_info))))
          goto create_error;

        name_buffer_ptr= strend(name_buffer_ptr) + 1;
        file++;
      }
    }
    else
    {
      create_partition_name(name_buff, path, name_buffer_ptr,
                            NORMAL_PART_NAME, FALSE);
      if ((error= set_up_table_before_create(table_arg, name_buff,
                                             create_info, part_elem)) ||
          ((error= (*file)->ha_create(name_buff, table_arg, create_info))))
        goto create_error;

      name_buffer_ptr= strend(name_buffer_ptr) + 1;
      file++;
    }
  }
  DBUG_RETURN(0);

create_error:
  name_buffer_ptr= m_name_buffer_ptr;
  for (abort_file= file, file= m_file; file < abort_file; file++)
  {
    create_partition_name(name_buff, path, name_buffer_ptr, NORMAL_PART_NAME,
                          FALSE);
    (void) (*file)->ha_delete_table((const char*) name_buff);
    name_buffer_ptr= strend(name_buffer_ptr) + 1;
  }
  handler::delete_table(name);
  DBUG_RETURN(error);
}


/*
  Drop partitions as part of ALTER TABLE of partitions

  SYNOPSIS
    drop_partitions()
    path                        Complete path of db and table name

  RETURN VALUE
    >0                          Failure
    0                           Success

  DESCRIPTION
    Use part_info object on handler object to deduce which partitions to
    drop (each partition has a state attached to it)
*/

int ha_partition::drop_partitions(const char *path)
{
  List_iterator<partition_element> part_it(m_part_info->partitions);
  char part_name_buff[FN_REFLEN];
  uint num_parts= m_part_info->partitions.elements;
  uint num_subparts= m_part_info->num_subparts;
  uint i= 0;
  uint name_variant;
  int  ret_error;
  int  error= 0;
  DBUG_ENTER("ha_partition::drop_partitions");

  /*
    Assert that it works without HA_FILE_BASED and lower_case_table_name = 2.
    We use m_file[0] as long as all partitions have the same storage engine.
  */
  DBUG_ASSERT(!strcmp(path, get_canonical_filename(m_file[0], path,
                                                   part_name_buff)));
  do
  {
    partition_element *part_elem= part_it++;
    if (part_elem->part_state == PART_TO_BE_DROPPED)
    {
      handler *file;
      /*
        This part is to be dropped, meaning the part or all its subparts.
      */
      name_variant= NORMAL_PART_NAME;
      if (m_is_sub_partitioned)
      {
        List_iterator<partition_element> sub_it(part_elem->subpartitions);
        uint j= 0, part;
        do
        {
          partition_element *sub_elem= sub_it++;
          part= i * num_subparts + j;
          create_subpartition_name(part_name_buff, path,
                                   part_elem->partition_name,
                                   sub_elem->partition_name, name_variant);
          file= m_file[part];
          DBUG_PRINT("info", ("Drop subpartition %s", part_name_buff));
          if ((ret_error= file->ha_delete_table(part_name_buff)))
            error= ret_error;
          if (deactivate_ddl_log_entry(sub_elem->log_entry->entry_pos))
            error= 1;
        } while (++j < num_subparts);
      }
      else
      {
        create_partition_name(part_name_buff, path,
                              part_elem->partition_name, name_variant,
                              TRUE);
        file= m_file[i];
        DBUG_PRINT("info", ("Drop partition %s", part_name_buff));
        if ((ret_error= file->ha_delete_table(part_name_buff)))
          error= ret_error;
        if (deactivate_ddl_log_entry(part_elem->log_entry->entry_pos))
          error= 1;
      }
      if (part_elem->part_state == PART_IS_CHANGED)
        part_elem->part_state= PART_NORMAL;
      else
        part_elem->part_state= PART_IS_DROPPED;
    }
  } while (++i < num_parts);
  (void) sync_ddl_log();
  DBUG_RETURN(error);
}


/*
  Rename partitions as part of ALTER TABLE of partitions

  SYNOPSIS
    rename_partitions()
    path                        Complete path of db and table name

  RETURN VALUE
    TRUE                        Failure
    FALSE                       Success

  DESCRIPTION
    When reorganising partitions, adding hash partitions and coalescing
    partitions it can be necessary to rename partitions while holding
    an exclusive lock on the table.
    Which partitions to rename is given by state of partitions found by the
    partition info struct referenced from the handler object
*/

int ha_partition::rename_partitions(const char *path)
{
  List_iterator<partition_element> part_it(m_part_info->partitions);
  List_iterator<partition_element> temp_it(m_part_info->temp_partitions);
  char part_name_buff[FN_REFLEN];
  char norm_name_buff[FN_REFLEN];
  uint num_parts= m_part_info->partitions.elements;
  uint part_count= 0;
  uint num_subparts= m_part_info->num_subparts;
  uint i= 0;
  uint j= 0;
  int error= 0;
  int ret_error;
  uint temp_partitions= m_part_info->temp_partitions.elements;
  handler *file;
  partition_element *part_elem, *sub_elem;
  DBUG_ENTER("ha_partition::rename_partitions");

  /*
    Assert that it works without HA_FILE_BASED and lower_case_table_name = 2.
    We use m_file[0] as long as all partitions have the same storage engine.
  */
  DBUG_ASSERT(!strcmp(path, get_canonical_filename(m_file[0], path,
                                                   norm_name_buff)));

  DEBUG_SYNC(ha_thd(), "before_rename_partitions");
  if (temp_partitions)
  {
    /*
      These are the reorganised partitions that have already been copied.
      We delete the partitions and log the delete by inactivating the
      delete log entry in the table log. We only need to synchronise
      these writes before moving to the next loop since there is no
      interaction among reorganised partitions, they cannot have the
      same name.
    */
    do
    {
      part_elem= temp_it++;
      if (m_is_sub_partitioned)
      {
        List_iterator<partition_element> sub_it(part_elem->subpartitions);
        j= 0;
        do
        {
          sub_elem= sub_it++;
          file= m_reorged_file[part_count++];
          create_subpartition_name(norm_name_buff, path,
                                   part_elem->partition_name,
                                   sub_elem->partition_name,
                                   NORMAL_PART_NAME);
          DBUG_PRINT("info", ("Delete subpartition %s", norm_name_buff));
          if ((ret_error= file->ha_delete_table(norm_name_buff)))
            error= ret_error;
          else if (deactivate_ddl_log_entry(sub_elem->log_entry->entry_pos))
            error= 1;
          else
            sub_elem->log_entry= NULL; /* Indicate success */
        } while (++j < num_subparts);
      }
      else
      {
        file= m_reorged_file[part_count++];
        create_partition_name(norm_name_buff, path,
                              part_elem->partition_name, NORMAL_PART_NAME,
                              TRUE);
        DBUG_PRINT("info", ("Delete partition %s", norm_name_buff));
        if ((ret_error= file->ha_delete_table(norm_name_buff)))
          error= ret_error;
        else if (deactivate_ddl_log_entry(part_elem->log_entry->entry_pos))
          error= 1;
        else
          part_elem->log_entry= NULL; /* Indicate success */
      }
    } while (++i < temp_partitions);
    (void) sync_ddl_log();
  }
  i= 0;
  do
  {
    /*
       When state is PART_IS_CHANGED it means that we have created a new
       TEMP partition that is to be renamed to normal partition name and
       we are to delete the old partition with currently the normal name.
       
       We perform this operation by
       1) Delete old partition with normal partition name
       2) Signal this in table log entry
       3) Synch table log to ensure we have consistency in crashes
       4) Rename temporary partition name to normal partition name
       5) Signal this to table log entry
       It is not necessary to synch the last state since a new rename
       should not corrupt things if there was no temporary partition.

       The only other parts we need to cater for are new parts that
       replace reorganised parts. The reorganised parts were deleted
       by the code above that goes through the temp_partitions list.
       Thus the synch above makes it safe to simply perform step 4 and 5
       for those entries.
    */
    part_elem= part_it++;
    if (part_elem->part_state == PART_IS_CHANGED ||
        part_elem->part_state == PART_TO_BE_DROPPED ||
        (part_elem->part_state == PART_IS_ADDED && temp_partitions))
    {
      if (m_is_sub_partitioned)
      {
        List_iterator<partition_element> sub_it(part_elem->subpartitions);
        uint part;

        j= 0;
        do
        {
          sub_elem= sub_it++;
          part= i * num_subparts + j;
          create_subpartition_name(norm_name_buff, path,
                                   part_elem->partition_name,
                                   sub_elem->partition_name,
                                   NORMAL_PART_NAME);
          if (part_elem->part_state == PART_IS_CHANGED)
          {
            file= m_reorged_file[part_count++];
            DBUG_PRINT("info", ("Delete subpartition %s", norm_name_buff));
            if ((ret_error= file->ha_delete_table(norm_name_buff)))
              error= ret_error;
            else if (deactivate_ddl_log_entry(sub_elem->log_entry->entry_pos))
              error= 1;
            (void) sync_ddl_log();
          }
          file= m_new_file[part];
          create_subpartition_name(part_name_buff, path,
                                   part_elem->partition_name,
                                   sub_elem->partition_name,
                                   TEMP_PART_NAME);
          DBUG_PRINT("info", ("Rename subpartition from %s to %s",
                     part_name_buff, norm_name_buff));
          if ((ret_error= file->ha_rename_table(part_name_buff,
                                                norm_name_buff)))
            error= ret_error;
          else if (deactivate_ddl_log_entry(sub_elem->log_entry->entry_pos))
            error= 1;
          else
            sub_elem->log_entry= NULL;
        } while (++j < num_subparts);
      }
      else
      {
        create_partition_name(norm_name_buff, path,
                              part_elem->partition_name, NORMAL_PART_NAME,
                              TRUE);
        if (part_elem->part_state == PART_IS_CHANGED)
        {
          file= m_reorged_file[part_count++];
          DBUG_PRINT("info", ("Delete partition %s", norm_name_buff));
          if ((ret_error= file->ha_delete_table(norm_name_buff)))
            error= ret_error;
          else if (deactivate_ddl_log_entry(part_elem->log_entry->entry_pos))
            error= 1;
          (void) sync_ddl_log();
        }
        file= m_new_file[i];
        create_partition_name(part_name_buff, path,
                              part_elem->partition_name, TEMP_PART_NAME,
                              TRUE);
        DBUG_PRINT("info", ("Rename partition from %s to %s",
                   part_name_buff, norm_name_buff));
        if ((ret_error= file->ha_rename_table(part_name_buff,
                                              norm_name_buff)))
          error= ret_error;
        else if (deactivate_ddl_log_entry(part_elem->log_entry->entry_pos))
          error= 1;
        else
          part_elem->log_entry= NULL;
      }
    }
  } while (++i < num_parts);
  (void) sync_ddl_log();
  DBUG_RETURN(error);
}


#define OPTIMIZE_PARTS 1
#define ANALYZE_PARTS 2
#define CHECK_PARTS   3
#define REPAIR_PARTS 4
#define ASSIGN_KEYCACHE_PARTS 5
#define PRELOAD_KEYS_PARTS 6

static const char *opt_op_name[]= {NULL,
                                   "optimize", "analyze", "check", "repair",
                                   "assign_to_keycache", "preload_keys"};

/*
  Optimize table

  SYNOPSIS
    optimize()
    thd               Thread object
    check_opt         Check/analyze/repair/optimize options

  RETURN VALUES
    >0                Error
    0                 Success
*/

int ha_partition::optimize(THD *thd, HA_CHECK_OPT *check_opt)
{
  DBUG_ENTER("ha_partition::optimize");

  DBUG_RETURN(handle_opt_partitions(thd, check_opt, OPTIMIZE_PARTS));
}


/*
  Analyze table

  SYNOPSIS
    analyze()
    thd               Thread object
    check_opt         Check/analyze/repair/optimize options

  RETURN VALUES
    >0                Error
    0                 Success
*/

int ha_partition::analyze(THD *thd, HA_CHECK_OPT *check_opt)
{
  DBUG_ENTER("ha_partition::analyze");

  DBUG_RETURN(handle_opt_partitions(thd, check_opt, ANALYZE_PARTS));
}


/*
  Check table

  SYNOPSIS
    check()
    thd               Thread object
    check_opt         Check/analyze/repair/optimize options

  RETURN VALUES
    >0                Error
    0                 Success
*/

int ha_partition::check(THD *thd, HA_CHECK_OPT *check_opt)
{
  DBUG_ENTER("ha_partition::check");

  DBUG_RETURN(handle_opt_partitions(thd, check_opt, CHECK_PARTS));
}


/*
  Repair table

  SYNOPSIS
    repair()
    thd               Thread object
    check_opt         Check/analyze/repair/optimize options

  RETURN VALUES
    >0                Error
    0                 Success
*/

int ha_partition::repair(THD *thd, HA_CHECK_OPT *check_opt)
{
  DBUG_ENTER("ha_partition::repair");

  DBUG_RETURN(handle_opt_partitions(thd, check_opt, REPAIR_PARTS));
}

int ha_partition::assign_to_keycache(THD *thd, HA_CHECK_OPT *check_opt)
{
  DBUG_ENTER("ha_partition::assign_to_keycache");

  DBUG_RETURN(handle_opt_partitions(thd, check_opt, ASSIGN_KEYCACHE_PARTS));
}


int ha_partition::preload_keys(THD *thd, HA_CHECK_OPT *check_opt)
{
  DBUG_ENTER("ha_partition::preload_keys");

  DBUG_RETURN(handle_opt_partitions(thd, check_opt, PRELOAD_KEYS_PARTS));
}

 
/*
  Handle optimize/analyze/check/repair of one partition

  SYNOPSIS
    handle_opt_part()
    thd                      Thread object
    check_opt                Options
    file                     Handler object of partition
    flag                     Optimize/Analyze/Check/Repair flag

  RETURN VALUE
    >0                        Failure
    0                         Success
*/

int ha_partition::handle_opt_part(THD *thd, HA_CHECK_OPT *check_opt,
                                  uint part_id, uint flag)
{
  int error;
  handler *file= m_file[part_id];
  DBUG_ENTER("handle_opt_part");
  DBUG_PRINT("enter", ("flag = %u", flag));

  if (flag == OPTIMIZE_PARTS)
    error= file->ha_optimize(thd, check_opt);
  else if (flag == ANALYZE_PARTS)
    error= file->ha_analyze(thd, check_opt);
  else if (flag == CHECK_PARTS)
  {
    error= file->ha_check(thd, check_opt);
    if (!error ||
        error == HA_ADMIN_ALREADY_DONE ||
        error == HA_ADMIN_NOT_IMPLEMENTED)
    {
      if (check_opt->flags & (T_MEDIUM | T_EXTEND))
        error= check_misplaced_rows(part_id, false);
    }
  }
  else if (flag == REPAIR_PARTS)
  {
    error= file->ha_repair(thd, check_opt);
    if (!error ||
        error == HA_ADMIN_ALREADY_DONE ||
        error == HA_ADMIN_NOT_IMPLEMENTED)
    {
      if (check_opt->flags & (T_MEDIUM | T_EXTEND))
        error= check_misplaced_rows(part_id, true);
    }
  }
  else if (flag == ASSIGN_KEYCACHE_PARTS)
    error= file->assign_to_keycache(thd, check_opt);
  else if (flag == PRELOAD_KEYS_PARTS)
    error= file->preload_keys(thd, check_opt);
  else
  {
    DBUG_ASSERT(FALSE);
    error= 1;
  }
  if (error == HA_ADMIN_ALREADY_DONE)
    error= 0;
  DBUG_RETURN(error);
}


/*
   print a message row formatted for ANALYZE/CHECK/OPTIMIZE/REPAIR TABLE
   (modelled after mi_check_print_msg)
   TODO: move this into the handler, or rewrite mysql_admin_table.
*/
static bool print_admin_msg(THD* thd, uint len,
                            const char* msg_type,
                            const char* db_name, const char* table_name,
                            const char* op_name, const char *fmt, ...)
  ATTRIBUTE_FORMAT(printf, 7, 8);
static bool print_admin_msg(THD* thd, uint len,
                            const char* msg_type,
                            const char* db_name, const char* table_name,
                            const char* op_name, const char *fmt, ...)
{
  va_list args;
  Protocol *protocol= thd->protocol;
  uint length;
  uint msg_length;
  char name[NAME_LEN*2+2];
  char *msgbuf;
  bool error= true;

  if (!(msgbuf= (char*) my_malloc(len, MYF(0))))
    return true;
  va_start(args, fmt);
  msg_length= my_vsnprintf(msgbuf, len, fmt, args);
  va_end(args);
  if (msg_length >= (len - 1))
    goto err;
  msgbuf[len - 1] = 0; // healthy paranoia


  if (!thd->vio_ok())
  {
    sql_print_error("%s", msgbuf);
    goto err;
  }

  length=(uint) (strxmov(name, db_name, ".", table_name,NullS) - name);
  /*
     TODO: switch from protocol to push_warning here. The main reason we didn't
     it yet is parallel repair. Due to following trace:
     mi_check_print_msg/push_warning/sql_alloc/my_pthread_getspecific_ptr.

     Also we likely need to lock mutex here (in both cases with protocol and
     push_warning).
  */
  DBUG_PRINT("info",("print_admin_msg:  %s, %s, %s, %s", name, op_name,
                     msg_type, msgbuf));
  protocol->prepare_for_resend();
  protocol->store(name, length, system_charset_info);
  protocol->store(op_name, system_charset_info);
  protocol->store(msg_type, system_charset_info);
  protocol->store(msgbuf, msg_length, system_charset_info);
  if (protocol->write())
  {
    sql_print_error("Failed on my_net_write, writing to stderr instead: %s\n",
                    msgbuf);
    goto err;
  }
  error= false;
err:
  my_free(msgbuf);
  return error;
}


/*
  Handle optimize/analyze/check/repair of partitions

  SYNOPSIS
    handle_opt_partitions()
    thd                      Thread object
    check_opt                Options
    flag                     Optimize/Analyze/Check/Repair flag

  RETURN VALUE
    >0                        Failure
    0                         Success
*/

int ha_partition::handle_opt_partitions(THD *thd, HA_CHECK_OPT *check_opt,
                                        uint flag)
{
  List_iterator<partition_element> part_it(m_part_info->partitions);
  uint num_parts= m_part_info->num_parts;
  uint num_subparts= m_part_info->num_subparts;
  uint i= 0;
  int error;
  DBUG_ENTER("ha_partition::handle_opt_partitions");
  DBUG_PRINT("enter", ("flag= %u", flag));

  do
  {
    partition_element *part_elem= part_it++;
    /*
      when ALTER TABLE <CMD> PARTITION ...
      it should only do named partitions, otherwise all partitions
    */
    if (!(thd->lex->alter_info.flags & Alter_info::ALTER_ADMIN_PARTITION) ||
        part_elem->part_state == PART_ADMIN)
    {
      if (m_is_sub_partitioned)
      {
        List_iterator<partition_element> subpart_it(part_elem->subpartitions);
        partition_element *sub_elem;
        uint j= 0, part;
        do
        {
          sub_elem= subpart_it++;
          part= i * num_subparts + j;
          DBUG_PRINT("info", ("Optimize subpartition %u (%s)",
                     part, sub_elem->partition_name));
          if ((error= handle_opt_part(thd, check_opt, part, flag)))
          {
            /* print a line which partition the error belongs to */
            if (error != HA_ADMIN_NOT_IMPLEMENTED &&
                error != HA_ADMIN_ALREADY_DONE &&
                error != HA_ADMIN_TRY_ALTER)
            {
              print_admin_msg(thd, MI_MAX_MSG_BUF, "error",
                              table_share->db.str, table->alias,
                              opt_op_name[flag],
                              "Subpartition %s returned error", 
                              sub_elem->partition_name);
            }
            /* reset part_state for the remaining partitions */
            do
            {
              if (part_elem->part_state == PART_ADMIN)
                part_elem->part_state= PART_NORMAL;
            } while ((part_elem= part_it++));
            DBUG_RETURN(error);
          }
        } while (++j < num_subparts);
      }
      else
      {
        DBUG_PRINT("info", ("Optimize partition %u (%s)", i,
                            part_elem->partition_name));
        if ((error= handle_opt_part(thd, check_opt, i, flag)))
        {
          /* print a line which partition the error belongs to */
          if (error != HA_ADMIN_NOT_IMPLEMENTED &&
              error != HA_ADMIN_ALREADY_DONE &&
              error != HA_ADMIN_TRY_ALTER)
          {
            print_admin_msg(thd, MI_MAX_MSG_BUF, "error",
                            table_share->db.str, table->alias,
                            opt_op_name[flag], "Partition %s returned error",
                            part_elem->partition_name);
          }
          /* reset part_state for the remaining partitions */
          do
          {
            if (part_elem->part_state == PART_ADMIN)
              part_elem->part_state= PART_NORMAL;
          } while ((part_elem= part_it++));
          DBUG_RETURN(error);
        }
      }
      part_elem->part_state= PART_NORMAL;
    }
  } while (++i < num_parts);
  DBUG_RETURN(FALSE);
}


bool ha_partition::check_and_repair(THD *thd)
{
  handler **file= m_file;
  DBUG_ENTER("ha_partition::check_and_repair");

  do
  {
    if ((*file)->ha_check_and_repair(thd))
      DBUG_RETURN(TRUE);
  } while (*(++file));
  DBUG_RETURN(FALSE);
}
 

bool ha_partition::auto_repair() const
{
  DBUG_ENTER("ha_partition::auto_repair");

  /*
    As long as we only support one storage engine per table,
    we can use the first partition for this function.
  */
  DBUG_RETURN(m_file[0]->auto_repair());
}


bool ha_partition::is_crashed() const
{
  handler **file= m_file;
  DBUG_ENTER("ha_partition::is_crashed");

  do
  {
    if ((*file)->is_crashed())
      DBUG_RETURN(TRUE);
  } while (*(++file));
  DBUG_RETURN(FALSE);
}
 

/*
  Prepare by creating a new partition

  SYNOPSIS
    prepare_new_partition()
    table                      Table object
    create_info                Create info from CREATE TABLE
    file                       Handler object of new partition
    part_name                  partition name

  RETURN VALUE
    >0                         Error
    0                          Success
*/

int ha_partition::prepare_new_partition(TABLE *tbl,
                                        HA_CREATE_INFO *create_info,
                                        handler *file, const char *part_name,
                                        partition_element *p_elem)
{
  int error;
  DBUG_ENTER("prepare_new_partition");

  /*
    This call to set_up_table_before_create() is done for an alter table.
    So this may be the second time around for this partition_element,
    depending on how many partitions and subpartitions there were before,
    and how many there are now.
    The first time, on the CREATE, data_file_name and index_file_name
    came from the parser.  They did not have the file name attached to
    the end.  But if this partition is less than the total number of
    previous partitions, it's data_file_name has the filename attached.
    So we need to take the partition filename off if it exists.
    That file name may be different from part_name, which will be
    attached in append_file_to_dir().
  */
  truncate_partition_filename(p_elem->data_file_name);
  truncate_partition_filename(p_elem->index_file_name);

  if ((error= set_up_table_before_create(tbl, part_name, create_info, p_elem)))
    goto error_create;

  if ((error= file->ha_create(part_name, tbl, create_info)))
  {
    /*
      Added for safety, InnoDB reports HA_ERR_FOUND_DUPP_KEY
      if the table/partition already exists.
      If we return that error code, then print_error would try to
      get_dup_key on a non-existing partition.
      So return a more reasonable error code.
    */
    if (error == HA_ERR_FOUND_DUPP_KEY)
      error= HA_ERR_TABLE_EXIST;
    goto error_create;
  }
  DBUG_PRINT("info", ("partition %s created", part_name));
  if ((error= file->ha_open(tbl, part_name, m_mode,
                            m_open_test_lock | HA_OPEN_NO_PSI_CALL)))
    goto error_open;
  DBUG_PRINT("info", ("partition %s opened", part_name));
  /*
    Note: if you plan to add another call that may return failure,
    better to do it before external_lock() as cleanup_new_partition()
    assumes that external_lock() is last call that may fail here.
    Otherwise see description for cleanup_new_partition().
  */
  if ((error= file->ha_external_lock(ha_thd(), F_WRLCK)))
    goto error_external_lock;
  DBUG_PRINT("info", ("partition %s external locked", part_name));

  DBUG_RETURN(0);
error_external_lock:
  (void) file->ha_close();
error_open:
  (void) file->ha_delete_table(part_name);
error_create:
  DBUG_RETURN(error);
}


/*
  Cleanup by removing all created partitions after error

  SYNOPSIS
    cleanup_new_partition()
    part_count             Number of partitions to remove

  RETURN VALUE
    NONE

  DESCRIPTION
    This function is called immediately after prepare_new_partition() in
    case the latter fails.

    In prepare_new_partition() last call that may return failure is
    external_lock(). That means if prepare_new_partition() fails,
    partition does not have external lock. Thus no need to call
    external_lock(F_UNLCK) here.

  TODO:
    We must ensure that in the case that we get an error during the process
    that we call external_lock with F_UNLCK, close the table and delete the
    table in the case where we have been successful with prepare_handler.
    We solve this by keeping an array of successful calls to prepare_handler
    which can then be used to undo the call.
*/

void ha_partition::cleanup_new_partition(uint part_count)
{
  DBUG_ENTER("ha_partition::cleanup_new_partition");

  if (m_added_file)
  {
    THD *thd= ha_thd();
    handler **file= m_added_file;
    while ((part_count > 0) && (*file))
    {
      (*file)->ha_external_lock(thd, F_UNLCK);
      (*file)->ha_close();

      /* Leave the (*file)->ha_delete_table(part_name) to the ddl-log */

      file++;
      part_count--;
    }
    m_added_file= NULL;
  }
  DBUG_VOID_RETURN;
}

/*
  Implement the partition changes defined by ALTER TABLE of partitions

  SYNOPSIS
    change_partitions()
    create_info                 HA_CREATE_INFO object describing all
                                fields and indexes in table
    path                        Complete path of db and table name
    out: copied                 Output parameter where number of copied
                                records are added
    out: deleted                Output parameter where number of deleted
                                records are added
    pack_frm_data               Reference to packed frm file
    pack_frm_len                Length of packed frm file

  RETURN VALUE
    >0                        Failure
    0                         Success

  DESCRIPTION
    Add and copy if needed a number of partitions, during this operation
    no other operation is ongoing in the server. This is used by
    ADD PARTITION all types as well as by REORGANIZE PARTITION. For
    one-phased implementations it is used also by DROP and COALESCE
    PARTITIONs.
    One-phased implementation needs the new frm file, other handlers will
    get zero length and a NULL reference here.
*/

int ha_partition::change_partitions(HA_CREATE_INFO *create_info,
                                    const char *path,
                                    ulonglong * const copied,
                                    ulonglong * const deleted,
                                    const uchar *pack_frm_data
                                    __attribute__((unused)),
                                    size_t pack_frm_len
                                    __attribute__((unused)))
{
  List_iterator<partition_element> part_it(m_part_info->partitions);
  List_iterator <partition_element> t_it(m_part_info->temp_partitions);
  char part_name_buff[FN_REFLEN];
  uint num_parts= m_part_info->partitions.elements;
  uint num_subparts= m_part_info->num_subparts;
  uint i= 0;
  uint num_remain_partitions, part_count, orig_count;
  handler **new_file_array;
  int error= 1;
  bool first;
  uint temp_partitions= m_part_info->temp_partitions.elements;
  THD *thd= ha_thd();
  DBUG_ENTER("ha_partition::change_partitions");

  /*
    Assert that it works without HA_FILE_BASED and lower_case_table_name = 2.
    We use m_file[0] as long as all partitions have the same storage engine.
  */
  DBUG_ASSERT(!strcmp(path, get_canonical_filename(m_file[0], path,
                                                   part_name_buff)));
  m_reorged_parts= 0;
  if (!m_part_info->is_sub_partitioned())
    num_subparts= 1;

  /*
    Step 1:
      Calculate number of reorganised partitions and allocate space for
      their handler references.
  */
  if (temp_partitions)
  {
    m_reorged_parts= temp_partitions * num_subparts;
  }
  else
  {
    do
    {
      partition_element *part_elem= part_it++;
      if (part_elem->part_state == PART_CHANGED ||
          part_elem->part_state == PART_REORGED_DROPPED)
      {
        m_reorged_parts+= num_subparts;
      }
    } while (++i < num_parts);
  }
  if (m_reorged_parts &&
      !(m_reorged_file= (handler**)sql_calloc(sizeof(handler*)*
                                              (m_reorged_parts + 1))))
  {
    mem_alloc_error(sizeof(handler*)*(m_reorged_parts+1));
    DBUG_RETURN(HA_ERR_OUT_OF_MEM);
  }

  /*
    Step 2:
      Calculate number of partitions after change and allocate space for
      their handler references.
  */
  num_remain_partitions= 0;
  if (temp_partitions)
  {
    num_remain_partitions= num_parts * num_subparts;
  }
  else
  {
    part_it.rewind();
    i= 0;
    do
    {
      partition_element *part_elem= part_it++;
      if (part_elem->part_state == PART_NORMAL ||
          part_elem->part_state == PART_TO_BE_ADDED ||
          part_elem->part_state == PART_CHANGED)
      {
        num_remain_partitions+= num_subparts;
      }
    } while (++i < num_parts);
  }
  if (!(new_file_array= (handler**)sql_calloc(sizeof(handler*)*
                                            (2*(num_remain_partitions + 1)))))
  {
    mem_alloc_error(sizeof(handler*)*2*(num_remain_partitions+1));
    DBUG_RETURN(HA_ERR_OUT_OF_MEM);
  }
  m_added_file= &new_file_array[num_remain_partitions + 1];

  /*
    Step 3:
      Fill m_reorged_file with handler references and NULL at the end
  */
  if (m_reorged_parts)
  {
    i= 0;
    part_count= 0;
    first= TRUE;
    part_it.rewind();
    do
    {
      partition_element *part_elem= part_it++;
      if (part_elem->part_state == PART_CHANGED ||
          part_elem->part_state == PART_REORGED_DROPPED)
      {
        memcpy((void*)&m_reorged_file[part_count],
               (void*)&m_file[i*num_subparts],
               sizeof(handler*)*num_subparts);
        part_count+= num_subparts;
      }
      else if (first && temp_partitions &&
               part_elem->part_state == PART_TO_BE_ADDED)
      {
        /*
          When doing an ALTER TABLE REORGANIZE PARTITION a number of
          partitions is to be reorganised into a set of new partitions.
          The reorganised partitions are in this case in the temp_partitions
          list. We copy all of them in one batch and thus we only do this
          until we find the first partition with state PART_TO_BE_ADDED
          since this is where the new partitions go in and where the old
          ones used to be.
        */
        first= FALSE;
        DBUG_ASSERT(((i*num_subparts) + m_reorged_parts) <= m_file_tot_parts);
        memcpy((void*)m_reorged_file, &m_file[i*num_subparts],
               sizeof(handler*)*m_reorged_parts);
      }
    } while (++i < num_parts);
  }

  /*
    Step 4:
      Fill new_array_file with handler references. Create the handlers if
      needed.
  */
  i= 0;
  part_count= 0;
  orig_count= 0;
  first= TRUE;
  part_it.rewind();
  do
  {
    partition_element *part_elem= part_it++;
    if (part_elem->part_state == PART_NORMAL)
    {
      DBUG_ASSERT(orig_count + num_subparts <= m_file_tot_parts);
      memcpy((void*)&new_file_array[part_count], (void*)&m_file[orig_count],
             sizeof(handler*)*num_subparts);
      part_count+= num_subparts;
      orig_count+= num_subparts;
    }
    else if (part_elem->part_state == PART_CHANGED ||
             part_elem->part_state == PART_TO_BE_ADDED)
    {
      uint j= 0;
      Parts_share_refs *p_share_refs;
      /*
        The Handler_shares for each partition's handler can be allocated
        within this handler, since there will not be any more instances of the
        new partitions, until the table is reopened after the ALTER succeeded.
      */
      p_share_refs= new Parts_share_refs;
      if (!p_share_refs)
        DBUG_RETURN(HA_ERR_OUT_OF_MEM);
      if (p_share_refs->init(num_subparts))
        DBUG_RETURN(HA_ERR_OUT_OF_MEM);
      if (m_new_partitions_share_refs.push_back(p_share_refs))
        DBUG_RETURN(HA_ERR_OUT_OF_MEM);
      do
      {
        handler **new_file= &new_file_array[part_count++];
        if (!(*new_file=
              get_new_handler(table->s,
                              thd->mem_root,
                              part_elem->engine_type)))
        {
          mem_alloc_error(sizeof(handler));
          DBUG_RETURN(HA_ERR_OUT_OF_MEM);
        }
        if ((*new_file)->set_ha_share_ref(&p_share_refs->ha_shares[j]))
        {
          DBUG_RETURN(HA_ERR_OUT_OF_MEM);
        }
      } while (++j < num_subparts);
      if (part_elem->part_state == PART_CHANGED)
        orig_count+= num_subparts;
      else if (temp_partitions && first)
      {
        orig_count+= (num_subparts * temp_partitions);
        first= FALSE;
      }
    }
  } while (++i < num_parts);
  first= FALSE;
  /*
    Step 5:
      Create the new partitions and also open, lock and call external_lock
      on them to prepare them for copy phase and also for later close
      calls
  */
  i= 0;
  part_count= 0;
  part_it.rewind();
  do
  {
    partition_element *part_elem= part_it++;
    if (part_elem->part_state == PART_TO_BE_ADDED ||
        part_elem->part_state == PART_CHANGED)
    {
      /*
        A new partition needs to be created PART_TO_BE_ADDED means an
        entirely new partition and PART_CHANGED means a changed partition
        that will still exist with either more or less data in it.
      */
      uint name_variant= NORMAL_PART_NAME;
      if (part_elem->part_state == PART_CHANGED ||
          (part_elem->part_state == PART_TO_BE_ADDED && temp_partitions))
        name_variant= TEMP_PART_NAME;
      if (m_part_info->is_sub_partitioned())
      {
        List_iterator<partition_element> sub_it(part_elem->subpartitions);
        uint j= 0, part;
        do
        {
          partition_element *sub_elem= sub_it++;
          create_subpartition_name(part_name_buff, path,
                                   part_elem->partition_name,
                                   sub_elem->partition_name,
                                   name_variant);
          part= i * num_subparts + j;
          DBUG_PRINT("info", ("Add subpartition %s", part_name_buff));
          if ((error= prepare_new_partition(table, create_info,
                                            new_file_array[part],
                                            (const char *)part_name_buff,
                                            sub_elem)))
          {
            cleanup_new_partition(part_count);
            DBUG_RETURN(error);
          }
          m_added_file[part_count++]= new_file_array[part];
        } while (++j < num_subparts);
      }
      else
      {
        create_partition_name(part_name_buff, path,
                              part_elem->partition_name, name_variant,
                              TRUE);
        DBUG_PRINT("info", ("Add partition %s", part_name_buff));
        if ((error= prepare_new_partition(table, create_info,
                                          new_file_array[i],
                                          (const char *)part_name_buff,
                                          part_elem)))
        {
          cleanup_new_partition(part_count);
          DBUG_RETURN(error);
        }
        m_added_file[part_count++]= new_file_array[i];
      }
    }
  } while (++i < num_parts);

  /*
    Step 6:
      State update to prepare for next write of the frm file.
  */
  i= 0;
  part_it.rewind();
  do
  {
    partition_element *part_elem= part_it++;
    if (part_elem->part_state == PART_TO_BE_ADDED)
      part_elem->part_state= PART_IS_ADDED;
    else if (part_elem->part_state == PART_CHANGED)
      part_elem->part_state= PART_IS_CHANGED;
    else if (part_elem->part_state == PART_REORGED_DROPPED)
      part_elem->part_state= PART_TO_BE_DROPPED;
  } while (++i < num_parts);
  for (i= 0; i < temp_partitions; i++)
  {
    partition_element *part_elem= t_it++;
    DBUG_ASSERT(part_elem->part_state == PART_TO_BE_REORGED);
    part_elem->part_state= PART_TO_BE_DROPPED;
  }
  m_new_file= new_file_array;
  if ((error= copy_partitions(copied, deleted)))
  {
    /*
      Close and unlock the new temporary partitions.
      They will later be deleted through the ddl-log.
    */
    cleanup_new_partition(part_count);
  }
  DBUG_RETURN(error);
}


/*
  Copy partitions as part of ALTER TABLE of partitions

  SYNOPSIS
    copy_partitions()
    out:copied                 Number of records copied
    out:deleted                Number of records deleted

  RETURN VALUE
    >0                         Error code
    0                          Success

  DESCRIPTION
    change_partitions has done all the preparations, now it is time to
    actually copy the data from the reorganised partitions to the new
    partitions.
*/

int ha_partition::copy_partitions(ulonglong * const copied,
                                  ulonglong * const deleted)
{
  uint reorg_part= 0;
  int result= 0;
  longlong func_value;
  DBUG_ENTER("ha_partition::copy_partitions");

  if (m_part_info->linear_hash_ind)
  {
    if (m_part_info->part_type == HASH_PARTITION)
      set_linear_hash_mask(m_part_info, m_part_info->num_parts);
    else
      set_linear_hash_mask(m_part_info, m_part_info->num_subparts);
  }

  while (reorg_part < m_reorged_parts)
  {
    handler *file= m_reorged_file[reorg_part];
    uint32 new_part;

    late_extra_cache(reorg_part);
    if ((result= file->ha_rnd_init(1)))
      goto init_error;
    while (TRUE)
    {
      if ((result= file->ha_rnd_next(m_rec0)))
      {
        if (result == HA_ERR_RECORD_DELETED)
          continue;                              //Probably MyISAM
        if (result != HA_ERR_END_OF_FILE)
          goto error;
        /*
          End-of-file reached, break out to continue with next partition or
          end the copy process.
        */
        break;
      }
      /* Found record to insert into new handler */
      if (m_part_info->get_partition_id(m_part_info, &new_part,
                                        &func_value))
      {
        /*
           This record is in the original table but will not be in the new
           table since it doesn't fit into any partition any longer due to
           changed partitioning ranges or list values.
        */
        (*deleted)++;
      }
      else
      {
        THD *thd= ha_thd();
        /* Copy record to new handler */
        (*copied)++;
        tmp_disable_binlog(thd); /* Do not replicate the low-level changes. */
        result= m_new_file[new_part]->ha_write_row(m_rec0);
        reenable_binlog(thd);
        if (result)
          goto error;
      }
    }
    late_extra_no_cache(reorg_part);
    file->ha_rnd_end();
    reorg_part++;
  }
  DBUG_RETURN(FALSE);
error:
  m_reorged_file[reorg_part]->ha_rnd_end();
init_error:
  DBUG_RETURN(result);
}

/*
  Update create info as part of ALTER TABLE

  SYNOPSIS
    update_create_info()
    create_info                   Create info from ALTER TABLE

  RETURN VALUE
    NONE

  DESCRIPTION
  Forward this handler call to the storage engine foreach
  partition handler.  The data_file_name for each partition may
  need to be reset if the tablespace was moved.  Use a dummy
  HA_CREATE_INFO structure and transfer necessary data.
*/

void ha_partition::update_create_info(HA_CREATE_INFO *create_info)
{
  DBUG_ENTER("ha_partition::update_create_info");

  /*
    Fix for bug#38751, some engines needs info-calls in ALTER.
    Archive need this since it flushes in ::info.
    HA_STATUS_AUTO is optimized so it will not always be forwarded
    to all partitions, but HA_STATUS_VARIABLE will.
  */
  info(HA_STATUS_VARIABLE);

  info(HA_STATUS_AUTO);

  if (!(create_info->used_fields & HA_CREATE_USED_AUTO))
    create_info->auto_increment_value= stats.auto_increment_value;

  /*
    DATA DIRECTORY and INDEX DIRECTORY are never applied to the whole
    partitioned table, only its parts.
  */
  my_bool from_alter = (create_info->data_file_name == (const char*) -1);
  create_info->data_file_name= create_info->index_file_name = NULL;

  /*
  We do not need to update the individual partition DATA DIRECTORY settings
  since they can be changed by ALTER TABLE ... REORGANIZE PARTITIONS.
  */
  if (from_alter)
    DBUG_VOID_RETURN;

  /*
    send Handler::update_create_info() to the storage engine for each
    partition that currently has a handler object.  Using a dummy
    HA_CREATE_INFO structure to collect DATA and INDEX DIRECTORYs.
  */

  List_iterator<partition_element> part_it(m_part_info->partitions);
  partition_element *part_elem, *sub_elem;
  uint num_subparts= m_part_info->num_subparts;
  uint num_parts = num_subparts ? m_file_tot_parts / num_subparts
                                : m_file_tot_parts;
  HA_CREATE_INFO dummy_info;
  memset(&dummy_info, 0, sizeof(dummy_info));

  /*
  Since update_create_info() can be called from mysql_prepare_alter_table()
  when not all handlers are set up, we look for that condition first.
  If all handlers are not available, do not call update_create_info for any.
  */
  uint i, j, part;
  for (i= 0; i < num_parts; i++)
  {
    part_elem= part_it++;
    if (!part_elem)
      DBUG_VOID_RETURN;
    if (m_is_sub_partitioned)
    {
      List_iterator<partition_element> subpart_it(part_elem->subpartitions);
      for (j= 0; j < num_subparts; j++)
      {
        sub_elem= subpart_it++;
        if (!sub_elem)
          DBUG_VOID_RETURN;
        part= i * num_subparts + j;
        if (part >= m_file_tot_parts || !m_file[part])
          DBUG_VOID_RETURN;
      }
    }
    else
    {
      if (!m_file[i])
        DBUG_VOID_RETURN;
    }
  }
  part_it.rewind();

  for (i= 0; i < num_parts; i++)
  {
    part_elem= part_it++;
    DBUG_ASSERT(part_elem);
    if (m_is_sub_partitioned)
    {
      List_iterator<partition_element> subpart_it(part_elem->subpartitions);
      for (j= 0; j < num_subparts; j++)
      {
        sub_elem= subpart_it++;
        DBUG_ASSERT(sub_elem);
        part= i * num_subparts + j;
        DBUG_ASSERT(part < m_file_tot_parts && m_file[part]);
        if (ha_legacy_type(m_file[part]->ht) == DB_TYPE_INNODB)
        {
          dummy_info.data_file_name= dummy_info.index_file_name = NULL;
          m_file[part]->update_create_info(&dummy_info);

          if (dummy_info.data_file_name || sub_elem->data_file_name)
          {
            sub_elem->data_file_name = (char*) dummy_info.data_file_name;
          }
          if (dummy_info.index_file_name || sub_elem->index_file_name)
          {
            sub_elem->index_file_name = (char*) dummy_info.index_file_name;
          }
        }
      }
    }
    else
    {
      DBUG_ASSERT(m_file[i]);
      if (ha_legacy_type(m_file[i]->ht) == DB_TYPE_INNODB)
      {
        dummy_info.data_file_name= dummy_info.index_file_name= NULL;
        m_file[i]->update_create_info(&dummy_info);
        if (dummy_info.data_file_name || part_elem->data_file_name)
        {
          part_elem->data_file_name = (char*) dummy_info.data_file_name;
        }
        if (dummy_info.index_file_name || part_elem->index_file_name)
        {
          part_elem->index_file_name = (char*) dummy_info.index_file_name;
        }
      }
    }
  }
  DBUG_VOID_RETURN;
}


void ha_partition::change_table_ptr(TABLE *table_arg, TABLE_SHARE *share)
{
  handler **file_array;
  table= table_arg;
  table_share= share;
  /*
    m_file can be NULL when using an old cached table in DROP TABLE, when the
    table just has REMOVED PARTITIONING, see Bug#42438
  */
  if (m_file)
  {
    file_array= m_file;
    DBUG_ASSERT(*file_array);
    do
    {
      (*file_array)->change_table_ptr(table_arg, share);
    } while (*(++file_array));
  }

  if (m_added_file && m_added_file[0])
  {
    /* if in middle of a drop/rename etc */
    file_array= m_added_file;
    do
    {
      (*file_array)->change_table_ptr(table_arg, share);
    } while (*(++file_array));
  }
}

/*
  Change comments specific to handler

  SYNOPSIS
    update_table_comment()
    comment                       Original comment

  RETURN VALUE
    new comment 

  DESCRIPTION
    No comment changes so far
*/

char *ha_partition::update_table_comment(const char *comment)
{
  return (char*) comment;                       /* Nothing to change */
}


int ha_partition::del_ren_table(const char *from, const char *to)
{
  int save_error= 0;
  int error= HA_ERR_INTERNAL_ERROR;
  char from_buff[FN_REFLEN], to_buff[FN_REFLEN], from_lc_buff[FN_REFLEN],
       to_lc_buff[FN_REFLEN], buff[FN_REFLEN];
  char *name_buffer_ptr;
  const char *from_path;
  const char *to_path= NULL;
  uint i;
  handler **file, **abort_file;
  DBUG_ENTER("ha_partition::del_ren_table");

  fn_format(buff,from, "", ha_par_ext, MY_APPEND_EXT);
  /* Check if the  par file exists */
  if (my_access(buff,F_OK))
  {
    /*
      If the .par file does not exist, return HA_ERR_NO_SUCH_TABLE,
      This will signal to the caller that it can remove the .frm
      file.
    */
    error= HA_ERR_NO_SUCH_TABLE;
    DBUG_RETURN(error);
  }

  if (get_from_handler_file(from, ha_thd()->mem_root, false))
    DBUG_RETURN(error);
  DBUG_ASSERT(m_file_buffer);
  DBUG_PRINT("enter", ("from: (%s) to: (%s)", from, to ? to : "(nil)"));
  name_buffer_ptr= m_name_buffer_ptr;
  file= m_file;
  /*
    Since ha_partition has HA_FILE_BASED, it must alter underlying table names
    if they do not have HA_FILE_BASED and lower_case_table_names == 2.
    See Bug#37402, for Mac OS X.
    The appended #P#<partname>[#SP#<subpartname>] will remain in current case.
    Using the first partitions handler, since mixing handlers is not allowed.
  */
  from_path= get_canonical_filename(*file, from, from_lc_buff);
  if (to != NULL)
    to_path= get_canonical_filename(*file, to, to_lc_buff);
  i= 0;
  do
  {
    create_partition_name(from_buff, from_path, name_buffer_ptr,
                          NORMAL_PART_NAME, FALSE);

    if (to != NULL)
    {                                           // Rename branch
      create_partition_name(to_buff, to_path, name_buffer_ptr,
                            NORMAL_PART_NAME, FALSE);
      error= (*file)->ha_rename_table(from_buff, to_buff);
      if (error)
        goto rename_error;
    }
    else                                        // delete branch
    {
      error= (*file)->ha_delete_table(from_buff);
    }
    name_buffer_ptr= strend(name_buffer_ptr) + 1;
    if (error)
      save_error= error;
    i++;
  } while (*(++file));

  if (to == NULL)
  {
    DBUG_EXECUTE_IF("crash_before_deleting_par_file", DBUG_SUICIDE(););

    /* Delete the .par file. If error, break.*/
    if ((error= handler::delete_table(from)))
      DBUG_RETURN(error);

    DBUG_EXECUTE_IF("crash_after_deleting_par_file", DBUG_SUICIDE(););
  }

  if (to != NULL)
  {
    if ((error= handler::rename_table(from, to)))
    {
      /* Try to revert everything, ignore errors */
      (void) handler::rename_table(to, from);
      goto rename_error;
    }
  }
  DBUG_RETURN(save_error);
rename_error:
  name_buffer_ptr= m_name_buffer_ptr;
  for (abort_file= file, file= m_file; file < abort_file; file++)
  {
    /* Revert the rename, back from 'to' to the original 'from' */
    create_partition_name(from_buff, from_path, name_buffer_ptr,
                          NORMAL_PART_NAME, FALSE);
    create_partition_name(to_buff, to_path, name_buffer_ptr,
                          NORMAL_PART_NAME, FALSE);
    /* Ignore error here */
    (void) (*file)->ha_rename_table(to_buff, from_buff);
    name_buffer_ptr= strend(name_buffer_ptr) + 1;
  }
  DBUG_RETURN(error);
}


int ha_partition::set_up_table_before_create(TABLE *tbl,
                    const char *partition_name_with_path, 
                    HA_CREATE_INFO *info,
                    partition_element *part_elem)
{
  int error= 0;
  const char *partition_name;
  THD *thd= ha_thd();
  DBUG_ENTER("set_up_table_before_create");

  DBUG_ASSERT(part_elem);

  if (!part_elem)
    DBUG_RETURN(1);
  tbl->s->max_rows= part_elem->part_max_rows;
  tbl->s->min_rows= part_elem->part_min_rows;
  partition_name= strrchr(partition_name_with_path, FN_LIBCHAR);
  if ((part_elem->index_file_name &&
      (error= append_file_to_dir(thd,
                                 (const char**)&part_elem->index_file_name,
                                 partition_name+1))) ||
      (part_elem->data_file_name &&
      (error= append_file_to_dir(thd,
                                 (const char**)&part_elem->data_file_name,
                                 partition_name+1))))
  {
    DBUG_RETURN(error);
  }
  info->index_file_name= part_elem->index_file_name;
  info->data_file_name= part_elem->data_file_name;
  DBUG_RETURN(0);
}


/*
  Add two names together

  SYNOPSIS
    name_add()
    out:dest                          Destination string
    first_name                        First name
    sec_name                          Second name

  RETURN VALUE
    >0                                Error
    0                                 Success

  DESCRIPTION
    Routine used to add two names with '_' in between then. Service routine
    to create_handler_file
    Include the NULL in the count of characters since it is needed as separator
    between the partition names.
*/

static uint name_add(char *dest, const char *first_name, const char *sec_name)
{
  return (uint) (strxmov(dest, first_name, "#SP#", sec_name, NullS) -dest) + 1;
}


bool ha_partition::create_handler_file(const char *name)
{
  partition_element *part_elem, *subpart_elem;
  uint i, j, part_name_len, subpart_name_len;
  uint tot_partition_words, tot_name_len, num_parts;
  uint tot_parts= 0;
  uint tot_len_words, tot_len_byte, chksum, tot_name_words;
  char *name_buffer_ptr;
  uchar *file_buffer, *engine_array;
  bool result= TRUE;
  char file_name[FN_REFLEN];
  char part_name[FN_REFLEN];
  char subpart_name[FN_REFLEN];
  File file;
  List_iterator_fast <partition_element> part_it(m_part_info->partitions);
  DBUG_ENTER("create_handler_file");

  num_parts= m_part_info->partitions.elements;
  DBUG_PRINT("info", ("table name = %s, num_parts = %u", name,
                      num_parts));
  tot_name_len= 0;
  for (i= 0; i < num_parts; i++)
  {
    part_elem= part_it++;
    if (part_elem->part_state != PART_NORMAL &&
        part_elem->part_state != PART_TO_BE_ADDED &&
        part_elem->part_state != PART_CHANGED)
      continue;
    tablename_to_filename(part_elem->partition_name, part_name,
                          FN_REFLEN);
    part_name_len= strlen(part_name);
    if (!m_is_sub_partitioned)
    {
      tot_name_len+= part_name_len + 1;
      tot_parts++;
    }
    else
    {
      List_iterator_fast <partition_element> sub_it(part_elem->subpartitions);
      for (j= 0; j < m_part_info->num_subparts; j++)
      {
        subpart_elem= sub_it++;
        tablename_to_filename(subpart_elem->partition_name,
                              subpart_name,
                              FN_REFLEN);
        subpart_name_len= strlen(subpart_name);
        tot_name_len+= part_name_len + subpart_name_len + 5;
        tot_parts++;
      }
    }
  }
  /*
     File format:
     Length in words              4 byte
     Checksum                     4 byte
     Total number of partitions   4 byte
     Array of engine types        n * 4 bytes where
     n = (m_tot_parts + 3)/4
     Length of name part in bytes 4 bytes
     (Names in filename format)
     Name part                    m * 4 bytes where
     m = ((length_name_part + 3)/4)*4

     All padding bytes are zeroed
  */
  tot_partition_words= (tot_parts + PAR_WORD_SIZE - 1) / PAR_WORD_SIZE;
  tot_name_words= (tot_name_len + PAR_WORD_SIZE - 1) / PAR_WORD_SIZE;
  /* 4 static words (tot words, checksum, tot partitions, name length) */
  tot_len_words= 4 + tot_partition_words + tot_name_words;
  tot_len_byte= PAR_WORD_SIZE * tot_len_words;
  if (!(file_buffer= (uchar *) my_malloc(tot_len_byte, MYF(MY_ZEROFILL))))
    DBUG_RETURN(TRUE);
  engine_array= (file_buffer + PAR_ENGINES_OFFSET);
  name_buffer_ptr= (char*) (engine_array + tot_partition_words * PAR_WORD_SIZE
                            + PAR_WORD_SIZE);
  part_it.rewind();
  for (i= 0; i < num_parts; i++)
  {
    part_elem= part_it++;
    if (part_elem->part_state != PART_NORMAL &&
        part_elem->part_state != PART_TO_BE_ADDED &&
        part_elem->part_state != PART_CHANGED)
      continue;
    if (!m_is_sub_partitioned)
    {
      tablename_to_filename(part_elem->partition_name, part_name, FN_REFLEN);
      name_buffer_ptr= strmov(name_buffer_ptr, part_name)+1;
      *engine_array= (uchar) ha_legacy_type(part_elem->engine_type);
      DBUG_PRINT("info", ("engine: %u", *engine_array));
      engine_array++;
    }
    else
    {
      List_iterator_fast <partition_element> sub_it(part_elem->subpartitions);
      for (j= 0; j < m_part_info->num_subparts; j++)
      {
        subpart_elem= sub_it++;
        tablename_to_filename(part_elem->partition_name, part_name,
                              FN_REFLEN);
        tablename_to_filename(subpart_elem->partition_name, subpart_name,
                              FN_REFLEN);
        name_buffer_ptr+= name_add(name_buffer_ptr,
                                   part_name,
                                   subpart_name);
        *engine_array= (uchar) ha_legacy_type(subpart_elem->engine_type);
        DBUG_PRINT("info", ("engine: %u", *engine_array));
        engine_array++;
      }
    }
  }
  chksum= 0;
  int4store(file_buffer, tot_len_words);
  int4store(file_buffer + PAR_NUM_PARTS_OFFSET, tot_parts);
  int4store(file_buffer + PAR_ENGINES_OFFSET +
            (tot_partition_words * PAR_WORD_SIZE),
            tot_name_len);
  for (i= 0; i < tot_len_words; i++)
    chksum^= uint4korr(file_buffer + PAR_WORD_SIZE * i);
  int4store(file_buffer + PAR_CHECKSUM_OFFSET, chksum);
  /*
    Add .par extension to the file name.
    Create and write and close file
    to be used at open, delete_table and rename_table
  */
  fn_format(file_name, name, "", ha_par_ext, MY_APPEND_EXT);
  if ((file= mysql_file_create(key_file_partition,
                               file_name, CREATE_MODE, O_RDWR | O_TRUNC,
                               MYF(MY_WME))) >= 0)
  {
    result= mysql_file_write(file, (uchar *) file_buffer, tot_len_byte,
                             MYF(MY_WME | MY_NABP)) != 0;
    (void) mysql_file_close(file, MYF(0));
  }
  else
    result= TRUE;
  my_free(file_buffer);
  DBUG_RETURN(result);
}


void ha_partition::clear_handler_file()
{
  if (m_engine_array)
  {
    plugin_unlock_list(NULL, m_engine_array, m_tot_parts);
    my_free(m_engine_array);
    m_engine_array= NULL;
  }
  if (m_file_buffer)
  {
    my_free(m_file_buffer);
    m_file_buffer= NULL;
  }
}


bool ha_partition::create_handlers(MEM_ROOT *mem_root)
{
  uint i;
  uint alloc_len= (m_tot_parts + 1) * sizeof(handler*);
  handlerton *hton0;
  DBUG_ENTER("create_handlers");

  if (!(m_file= (handler **) alloc_root(mem_root, alloc_len)))
    DBUG_RETURN(TRUE);
  m_file_tot_parts= m_tot_parts;
  memset(m_file, 0, alloc_len);
  for (i= 0; i < m_tot_parts; i++)
  {
    handlerton *hton= plugin_data(m_engine_array[i], handlerton*);
    if (!(m_file[i]= get_new_handler(table_share, mem_root, hton)))
      DBUG_RETURN(TRUE);
    DBUG_PRINT("info", ("engine_type: %u", hton->db_type));
  }
  /* For the moment we only support partition over the same table engine */
  hton0= plugin_data(m_engine_array[0], handlerton*);
  if (hton0 == myisam_hton)
  {
    DBUG_PRINT("info", ("MyISAM"));
    m_myisam= TRUE;
  }
  /* INNODB may not be compiled in... */
  else if (ha_legacy_type(hton0) == DB_TYPE_INNODB)
  {
    DBUG_PRINT("info", ("InnoDB"));
    m_innodb= TRUE;
  }
  DBUG_RETURN(FALSE);
}


/*
  Create underlying handler objects from partition info

  SYNOPSIS
    new_handlers_from_part_info()
    mem_root            Allocate memory through this

  RETURN VALUE
    TRUE                  Error
    FALSE                 Success
*/

bool ha_partition::new_handlers_from_part_info(MEM_ROOT *mem_root)
{
  uint i, j, part_count;
  partition_element *part_elem;
  uint alloc_len= (m_tot_parts + 1) * sizeof(handler*);
  List_iterator_fast <partition_element> part_it(m_part_info->partitions);
  DBUG_ENTER("ha_partition::new_handlers_from_part_info");

  if (!(m_file= (handler **) alloc_root(mem_root, alloc_len)))
  {
    mem_alloc_error(alloc_len);
    goto error_end;
  }
  m_file_tot_parts= m_tot_parts;
  memset(m_file, 0, alloc_len);
  DBUG_ASSERT(m_part_info->num_parts > 0);

  i= 0;
  part_count= 0;
  /*
    Don't know the size of the underlying storage engine, invent a number of
    bytes allocated for error message if allocation fails
  */
  do
  {
    part_elem= part_it++;
    if (m_is_sub_partitioned)
    {
      for (j= 0; j < m_part_info->num_subparts; j++)
      {
        if (!(m_file[part_count++]= get_new_handler(table_share, mem_root,
                                                    part_elem->engine_type)))
          goto error;
        DBUG_PRINT("info", ("engine_type: %u",
                   (uint) ha_legacy_type(part_elem->engine_type)));
      }
    }
    else
    {
      if (!(m_file[part_count++]= get_new_handler(table_share, mem_root,
                                                  part_elem->engine_type)))
        goto error;
      DBUG_PRINT("info", ("engine_type: %u",
                 (uint) ha_legacy_type(part_elem->engine_type)));
    }
  } while (++i < m_part_info->num_parts);
  if (part_elem->engine_type == myisam_hton)
  {
    DBUG_PRINT("info", ("MyISAM"));
    m_myisam= TRUE;
  }
  DBUG_RETURN(FALSE);
error:
  mem_alloc_error(sizeof(handler));
error_end:
  DBUG_RETURN(TRUE);
}


bool ha_partition::read_par_file(const char *name)
{
  char buff[FN_REFLEN], *tot_name_len_offset, *buff_p= buff;
  File file;
  char *file_buffer;
  uint i, len_bytes, len_words, tot_partition_words, tot_name_words, chksum;
  DBUG_ENTER("ha_partition::read_par_file");
  DBUG_PRINT("enter", ("table name: '%s'", name));

  if (m_file_buffer)
    DBUG_RETURN(false);
  fn_format(buff, name, "", ha_par_ext, MY_APPEND_EXT);

  /* Following could be done with mysql_file_stat to read in whole file */
  if ((file= mysql_file_open(key_file_partition,
                             buff, O_RDONLY | O_SHARE, MYF(0))) < 0)
    DBUG_RETURN(TRUE);
  if (mysql_file_read(file, (uchar *) &buff[0], PAR_WORD_SIZE, MYF(MY_NABP)))
    goto err1;
  len_words= uint4korr(buff_p);
  len_bytes= PAR_WORD_SIZE * len_words;
  if (mysql_file_seek(file, 0, MY_SEEK_SET, MYF(0)) == MY_FILEPOS_ERROR)
    goto err1;
  if (!(file_buffer= (char*) my_malloc(len_bytes, MYF(0))))
    goto err1;
  if (mysql_file_read(file, (uchar *) file_buffer, len_bytes, MYF(MY_NABP)))
    goto err2;

  chksum= 0;
  for (i= 0; i < len_words; i++)
    chksum ^= uint4korr((file_buffer) + PAR_WORD_SIZE * i);
  if (chksum)
    goto err2;
  m_tot_parts= uint4korr((file_buffer) + PAR_NUM_PARTS_OFFSET);
  DBUG_PRINT("info", ("No of parts = %u", m_tot_parts));
  tot_partition_words= (m_tot_parts + PAR_WORD_SIZE - 1) / PAR_WORD_SIZE;

  tot_name_len_offset= file_buffer + PAR_ENGINES_OFFSET +
                       PAR_WORD_SIZE * tot_partition_words;
  tot_name_words= (uint4korr(tot_name_len_offset) + PAR_WORD_SIZE - 1) /
                  PAR_WORD_SIZE;
  /*
    Verify the total length = tot size word, checksum word, num parts word +
    engines array + name length word + name array.
  */
  if (len_words != (tot_partition_words + tot_name_words + 4))
    goto err2;
  (void) mysql_file_close(file, MYF(0));
  m_file_buffer= file_buffer;          // Will be freed in clear_handler_file()
  m_name_buffer_ptr= tot_name_len_offset + PAR_WORD_SIZE;

  DBUG_RETURN(false);

err2:
  my_free(file_buffer);
err1:
  (void) mysql_file_close(file, MYF(0));
  DBUG_RETURN(true);
}


bool ha_partition::setup_engine_array(MEM_ROOT *mem_root)
{
  uint i;
  uchar *buff;
  handlerton **engine_array, *first_engine;
  enum legacy_db_type db_type, first_db_type;

  DBUG_ASSERT(!m_file);
  DBUG_ENTER("ha_partition::setup_engine_array");
  engine_array= (handlerton **) my_alloca(m_tot_parts * sizeof(handlerton*));
  if (!engine_array)
    DBUG_RETURN(true);

  buff= (uchar *) (m_file_buffer + PAR_ENGINES_OFFSET);
  first_db_type= (enum legacy_db_type) buff[0];
  first_engine= ha_resolve_by_legacy_type(ha_thd(), first_db_type);
  if (!first_engine)
    goto err;

  if (!(m_engine_array= (plugin_ref*)
                my_malloc(m_tot_parts * sizeof(plugin_ref), MYF(MY_WME))))
    goto err;

  for (i= 0; i < m_tot_parts; i++)
  {
    db_type= (enum legacy_db_type) buff[i];
    if (db_type != first_db_type)
    {
      DBUG_PRINT("error", ("partition %u engine %d is not same as "
                           "first partition %d", i, db_type,
                           (int) first_db_type));
      DBUG_ASSERT(0);
      clear_handler_file();
      goto err;
    }
    m_engine_array[i]= ha_lock_engine(NULL, first_engine);
    if (!m_engine_array[i])
    {
      clear_handler_file();
      goto err;
    }
  }

  my_afree((gptr) engine_array);
    
  if (create_handlers(mem_root))
  {
    clear_handler_file();
    DBUG_RETURN(true);
  }

  DBUG_RETURN(false);

err:
  my_afree((gptr) engine_array);
  DBUG_RETURN(true);
}


bool ha_partition::get_from_handler_file(const char *name, MEM_ROOT *mem_root,
                                         bool is_clone)
{
  DBUG_ENTER("ha_partition::get_from_handler_file");
  DBUG_PRINT("enter", ("table name: '%s'", name));

  if (m_file_buffer)
    DBUG_RETURN(false);

  if (read_par_file(name))
    DBUG_RETURN(true);

  if (!is_clone && setup_engine_array(mem_root))
    DBUG_RETURN(true);

  DBUG_RETURN(false);
}


/****************************************************************************
                MODULE open/close object
****************************************************************************/

static uchar *get_part_name(PART_NAME_DEF *part, size_t *length,
                            my_bool not_used __attribute__((unused)))
{
  *length= part->length;
  return part->partition_name;
}


bool ha_partition::insert_partition_name_in_hash(const char *name, uint part_id,
                                                 bool is_subpart)
{
  PART_NAME_DEF *part_def;
  uchar *part_name;
  uint part_name_length;
  DBUG_ENTER("ha_partition::insert_partition_name_in_hash");
  /*
    Calculate and store the length here, to avoid doing it when
    searching the hash.
  */
  part_name_length= strlen(name);
  /*
    Must use memory that lives as long as table_share.
    Freed in the Partition_share destructor.
    Since we use my_multi_malloc, then my_free(part_def) will also free
    part_name, as a part of my_hash_free.
  */
  if (!my_multi_malloc(MY_WME,
                       &part_def, sizeof(PART_NAME_DEF),
                       &part_name, part_name_length + 1,
                       NULL))
    DBUG_RETURN(true);
  memcpy(part_name, name, part_name_length + 1);
  part_def->partition_name= part_name;
  part_def->length= part_name_length;
  part_def->part_id= part_id;
  part_def->is_subpart= is_subpart;
  if (my_hash_insert(&part_share->partition_name_hash, (uchar *) part_def))
  {
    my_free(part_def);
    DBUG_RETURN(true);
  }
  DBUG_RETURN(false);
}


bool ha_partition::populate_partition_name_hash()
{
  List_iterator<partition_element> part_it(m_part_info->partitions);
  uint num_parts= m_part_info->num_parts;
  uint num_subparts= m_is_sub_partitioned ? m_part_info->num_subparts : 1;
  uint tot_names;
  uint i= 0;
  DBUG_ASSERT(part_share);

  DBUG_ENTER("ha_partition::populate_partition_name_hash");

  /*
    partition_name_hash is only set once and never changed
    -> OK to check without locking.
  */

  if (part_share->partition_name_hash_initialized)
    DBUG_RETURN(false);
  lock_shared_ha_data();
  if (part_share->partition_name_hash_initialized)
  {
    unlock_shared_ha_data();
    DBUG_RETURN(false);
  }
  tot_names= m_is_sub_partitioned ? m_tot_parts + num_parts : num_parts;
  if (my_hash_init(&part_share->partition_name_hash,
                   system_charset_info, tot_names, 0, 0,
                   (my_hash_get_key) get_part_name,
                   my_free, HASH_UNIQUE))
  {
    unlock_shared_ha_data();
    DBUG_RETURN(TRUE);
  }

  do
  {
    partition_element *part_elem= part_it++;
    DBUG_ASSERT(part_elem->part_state == PART_NORMAL);
    if (part_elem->part_state == PART_NORMAL)
    {
      if (insert_partition_name_in_hash(part_elem->partition_name,
                                        i * num_subparts, false))
        goto err;
      if (m_is_sub_partitioned)
      {
        List_iterator<partition_element>
                                    subpart_it(part_elem->subpartitions);
        partition_element *sub_elem;
        uint j= 0;
        do
        {
          sub_elem= subpart_it++;
          if (insert_partition_name_in_hash(sub_elem->partition_name,
                                            i * num_subparts + j, true))
            goto err;

        } while (++j < num_subparts);
      }
    }
  } while (++i < num_parts);

  part_share->partition_name_hash_initialized= true;
  unlock_shared_ha_data();

  DBUG_RETURN(FALSE);
err:
  my_hash_free(&part_share->partition_name_hash);
  unlock_shared_ha_data();

  DBUG_RETURN(TRUE);
}


bool ha_partition::set_ha_share_ref(Handler_share **ha_share_arg)
{
  Handler_share **ha_shares;
  uint i;
  DBUG_ENTER("ha_partition::set_ha_share_ref");

  DBUG_ASSERT(!part_share);
  DBUG_ASSERT(table_share);
  DBUG_ASSERT(!m_is_clone_of);
  DBUG_ASSERT(m_tot_parts);
  if (handler::set_ha_share_ref(ha_share_arg))
    DBUG_RETURN(true);
  if (!(part_share= get_share()))
    DBUG_RETURN(true);
  DBUG_ASSERT(part_share->partitions_share_refs);
  DBUG_ASSERT(part_share->partitions_share_refs->num_parts >= m_tot_parts);
  ha_shares= part_share->partitions_share_refs->ha_shares;
  for (i= 0; i < m_tot_parts; i++)
  {
    if (m_file[i]->set_ha_share_ref(&ha_shares[i]))
      DBUG_RETURN(true);
  }
  DBUG_RETURN(false);
}


Partition_share *ha_partition::get_share()
{
  Partition_share *tmp_share;
  DBUG_ENTER("ha_partition::get_share");
  DBUG_ASSERT(table_share);

  lock_shared_ha_data();
  if (!(tmp_share= static_cast<Partition_share*>(get_ha_share_ptr())))
  {
    tmp_share= new Partition_share;
    if (!tmp_share)
      goto err;
    if (tmp_share->init(m_tot_parts))
    {
      delete tmp_share;
      tmp_share= NULL;
      goto err;
    }
    set_ha_share_ptr(static_cast<Handler_share*>(tmp_share));
  }
err:
  unlock_shared_ha_data();
  DBUG_RETURN(tmp_share);
}



void ha_partition::free_partition_bitmaps()
{
  /* Initialize the bitmap we use to minimize ha_start_bulk_insert calls */
  bitmap_free(&m_bulk_insert_started);
  bitmap_free(&m_locked_partitions);
  bitmap_free(&m_partitions_to_reset);
  bitmap_free(&m_key_not_found_partitions);
}


bool ha_partition::init_partition_bitmaps()
{
  DBUG_ENTER("ha_partition::init_partition_bitmaps");
  /* Initialize the bitmap we use to minimize ha_start_bulk_insert calls */
  if (bitmap_init(&m_bulk_insert_started, NULL, m_tot_parts + 1, FALSE))
    DBUG_RETURN(true);
  bitmap_clear_all(&m_bulk_insert_started);

  /* Initialize the bitmap we use to keep track of locked partitions */
  if (bitmap_init(&m_locked_partitions, NULL, m_tot_parts, FALSE))
  {
    bitmap_free(&m_bulk_insert_started);
    DBUG_RETURN(true);
  }
  bitmap_clear_all(&m_locked_partitions);

  /*
    Initialize the bitmap we use to keep track of partitions which may have
    something to reset in ha_reset().
  */
  if (bitmap_init(&m_partitions_to_reset, NULL, m_tot_parts, FALSE))
  {
    bitmap_free(&m_bulk_insert_started);
    bitmap_free(&m_locked_partitions);
    DBUG_RETURN(true);
  }
  bitmap_clear_all(&m_partitions_to_reset);

  /*
    Initialize the bitmap we use to keep track of partitions which returned
    HA_ERR_KEY_NOT_FOUND from index_read_map.
  */
  if (bitmap_init(&m_key_not_found_partitions, NULL, m_tot_parts, FALSE))
  {
    bitmap_free(&m_bulk_insert_started);
    bitmap_free(&m_locked_partitions);
    bitmap_free(&m_partitions_to_reset);
    DBUG_RETURN(true);
  }
  bitmap_clear_all(&m_key_not_found_partitions);
  m_key_not_found= false;
  /* Initialize the bitmap for read/lock_partitions */
  if (!m_is_clone_of)
  {
    DBUG_ASSERT(!m_clone_mem_root);
    if (m_part_info->set_partition_bitmaps(NULL))
    {
      free_partition_bitmaps();
      DBUG_RETURN(true);
    }
  }
  DBUG_RETURN(false);
}


/*
  Open handler object

  SYNOPSIS
    open()
    name                  Full path of table name
    mode                  Open mode flags
    test_if_locked        ?

  RETURN VALUE
    >0                    Error
    0                     Success

  DESCRIPTION
    Used for opening tables. The name will be the name of the file.
    A table is opened when it needs to be opened. For instance
    when a request comes in for a select on the table (tables are not
    open and closed for each request, they are cached).

    Called from handler.cc by handler::ha_open(). The server opens all tables
    by calling ha_open() which then calls the handler specific open().
*/

int ha_partition::open(const char *name, int mode, uint test_if_locked)
{
  char *name_buffer_ptr;
  int error= HA_ERR_INITIALIZATION;
  handler **file;
  char name_buff[FN_REFLEN];
  ulonglong check_table_flags;
  DBUG_ENTER("ha_partition::open");

  DBUG_ASSERT(table->s == table_share);
  ref_length= 0;
  m_mode= mode;
  m_open_test_lock= test_if_locked;
  m_part_field_array= m_part_info->full_part_field_array;
  if (get_from_handler_file(name, &table->mem_root, test(m_is_clone_of)))
    DBUG_RETURN(error);
  name_buffer_ptr= m_name_buffer_ptr;
  if (populate_partition_name_hash())
  {
    DBUG_RETURN(HA_ERR_INITIALIZATION);
  }
  m_start_key.length= 0;
  m_rec0= table->record[0];
  m_rec_length= table_share->reclength;
  if (!m_part_ids_sorted_by_num_of_records)
  {
    if (!(m_part_ids_sorted_by_num_of_records=
            (uint32*) my_malloc(m_tot_parts * sizeof(uint32), MYF(MY_WME))))
      DBUG_RETURN(error);
    uint32 i;
    /* Initialize it with all partition ids. */
    for (i= 0; i < m_tot_parts; i++)
      m_part_ids_sorted_by_num_of_records[i]= i;
  }

  if (init_partition_bitmaps())
    DBUG_RETURN(error);

  DBUG_ASSERT(m_part_info);

  if (m_is_clone_of)
  {
    uint i, alloc_len;
    DBUG_ASSERT(m_clone_mem_root);
    /* Allocate an array of handler pointers for the partitions handlers. */
    alloc_len= (m_tot_parts + 1) * sizeof(handler*);
    if (!(m_file= (handler **) alloc_root(m_clone_mem_root, alloc_len)))
    {
      error= HA_ERR_INITIALIZATION;
      goto err_alloc;
    }
    memset(m_file, 0, alloc_len);
    /*
      Populate them by cloning the original partitions. This also opens them.
      Note that file->ref is allocated too.
    */
    file= m_is_clone_of->m_file;
    for (i= 0; i < m_tot_parts; i++)
    {
      create_partition_name(name_buff, name, name_buffer_ptr, NORMAL_PART_NAME,
                            FALSE);
      /* ::clone() will also set ha_share from the original. */
      if (!(m_file[i]= file[i]->clone(name_buff, m_clone_mem_root)))
      {
        error= HA_ERR_INITIALIZATION;
        file= &m_file[i];
        goto err_handler;
      }
      name_buffer_ptr+= strlen(name_buffer_ptr) + 1;
    }
  }
  else
  {
   file= m_file;
   do
   {
      create_partition_name(name_buff, name, name_buffer_ptr, NORMAL_PART_NAME,
                            FALSE);
      if ((error= (*file)->ha_open(table, name_buff, mode,
                                   test_if_locked | HA_OPEN_NO_PSI_CALL)))
        goto err_handler;
      if (m_file == file)
        m_num_locks= (*file)->lock_count();
      DBUG_ASSERT(m_num_locks == (*file)->lock_count());
      name_buffer_ptr+= strlen(name_buffer_ptr) + 1;
    } while (*(++file));
  }
  
  file= m_file;
  ref_length= (*file)->ref_length;
  check_table_flags= (((*file)->ha_table_flags() &
                       ~(PARTITION_DISABLED_TABLE_FLAGS)) |
                      (PARTITION_ENABLED_TABLE_FLAGS));
  while (*(++file))
  {
    /* MyISAM can have smaller ref_length for partitions with MAX_ROWS set */
    set_if_bigger(ref_length, ((*file)->ref_length));
    /*
      Verify that all partitions have the same set of table flags.
      Mask all flags that partitioning enables/disables.
    */
    if (check_table_flags != (((*file)->ha_table_flags() &
                               ~(PARTITION_DISABLED_TABLE_FLAGS)) |
                              (PARTITION_ENABLED_TABLE_FLAGS)))
    {
      error= HA_ERR_INITIALIZATION;
      /* set file to last handler, so all of them are closed */
      file = &m_file[m_tot_parts - 1];
      goto err_handler;
    }
  }
  key_used_on_scan= m_file[0]->key_used_on_scan;
  implicit_emptied= m_file[0]->implicit_emptied;
  /*
    Add 2 bytes for partition id in position ref length.
    ref_length=max_in_all_partitions(ref_length) + PARTITION_BYTES_IN_POS
  */
  ref_length+= PARTITION_BYTES_IN_POS;
  m_ref_length= ref_length;

  /*
    Release buffer read from .par file. It will not be reused again after
    being opened once.
  */
  clear_handler_file();

  /*
    Some handlers update statistics as part of the open call. This will in
    some cases corrupt the statistics of the partition handler and thus
    to ensure we have correct statistics we call info from open after
    calling open on all individual handlers.
  */
  m_handler_status= handler_opened;
  if (m_part_info->part_expr)
    m_part_func_monotonicity_info=
                            m_part_info->part_expr->get_monotonicity_info();
  else if (m_part_info->list_of_part_fields)
    m_part_func_monotonicity_info= MONOTONIC_STRICT_INCREASING;
  info(HA_STATUS_VARIABLE | HA_STATUS_CONST);
  DBUG_RETURN(0);

err_handler:
  DEBUG_SYNC(ha_thd(), "partition_open_error");
  while (file-- != m_file)
    (*file)->ha_close();
err_alloc:
  free_partition_bitmaps();

  DBUG_RETURN(error);
}


/*
  Disabled since it is not possible to prune yet.
  without pruning, it need to rebind/unbind every partition in every
  statement which uses a table from the table cache. Will also use
  as many PSI_tables as there are partitions.
*/
#ifdef HAVE_M_PSI_PER_PARTITION
void ha_partition::unbind_psi()
{
  uint i;

  DBUG_ENTER("ha_partition::unbind_psi");
  handler::unbind_psi();
  for (i= 0; i < m_tot_parts; i++)
  {
    DBUG_ASSERT(m_file[i] != NULL);
    m_file[i]->unbind_psi();
  }
  DBUG_VOID_RETURN;
}

void ha_partition::rebind_psi()
{
  uint i;

  DBUG_ENTER("ha_partition::rebind_psi");
  handler::rebind_psi();
  for (i= 0; i < m_tot_parts; i++)
  {
    DBUG_ASSERT(m_file[i] != NULL);
    m_file[i]->rebind_psi();
  }
  DBUG_VOID_RETURN;
}
#endif /* HAVE_M_PSI_PER_PARTITION */


handler *ha_partition::clone(const char *name, MEM_ROOT *mem_root)
{
  ha_partition *new_handler;

  DBUG_ENTER("ha_partition::clone");
  new_handler= new (mem_root) ha_partition(ht, table_share, m_part_info,
                                           this, mem_root);
  if (!new_handler)
    DBUG_RETURN(NULL);

  /*
    We will not clone each partition's handler here, it will be done in
    ha_partition::open() for clones. Also set_ha_share_ref is not needed
    here, since 1) ha_share is copied in the constructor used above
    2) each partition's cloned handler will set it from its original.
  */

  /*
    Allocate new_handler->ref here because otherwise ha_open will allocate it
    on this->table->mem_root and we will not be able to reclaim that memory 
    when the clone handler object is destroyed.
  */
  if (!(new_handler->ref= (uchar*) alloc_root(mem_root,
                                              ALIGN_SIZE(m_ref_length)*2)))
    goto err;

  if (new_handler->ha_open(table, name,
                           table->db_stat,
                           HA_OPEN_IGNORE_IF_LOCKED | HA_OPEN_NO_PSI_CALL))
    goto err;

  DBUG_RETURN((handler*) new_handler);

err:
  delete new_handler;
  DBUG_RETURN(NULL);
}


/*
  Close handler object

  SYNOPSIS
    close()

  RETURN VALUE
    >0                   Error code
    0                    Success

  DESCRIPTION
    Called from sql_base.cc, sql_select.cc, and table.cc.
    In sql_select.cc it is only used to close up temporary tables or during
    the process where a temporary table is converted over to being a
    myisam table.
    For sql_base.cc look at close_data_tables().
*/

int ha_partition::close(void)
{
  bool first= TRUE;
  handler **file;
  DBUG_ENTER("ha_partition::close");

  DBUG_ASSERT(table->s == table_share);
  destroy_record_priority_queue();
  free_partition_bitmaps();
  DBUG_ASSERT(m_part_info);
  file= m_file;

repeat:
  do
  {
    (*file)->ha_close();
  } while (*(++file));

  if (first && m_added_file && m_added_file[0])
  {
    file= m_added_file;
    first= FALSE;
    goto repeat;
  }

  m_handler_status= handler_closed;
  DBUG_RETURN(0);
}

/****************************************************************************
                MODULE start/end statement
****************************************************************************/
/*
  A number of methods to define various constants for the handler. In
  the case of the partition handler we need to use some max and min
  of the underlying handlers in most cases.
*/

/*
  Set external locks on table

  SYNOPSIS
    external_lock()
    thd                    Thread object
    lock_type              Type of external lock

  RETURN VALUE
    >0                   Error code
    0                    Success

  DESCRIPTION
    First you should go read the section "locking functions for mysql" in
    lock.cc to understand this.
    This create a lock on the table. If you are implementing a storage engine
    that can handle transactions look at ha_berkeley.cc to see how you will
    want to go about doing this. Otherwise you should consider calling
    flock() here.
    Originally this method was used to set locks on file level to enable
    several MySQL Servers to work on the same data. For transactional
    engines it has been "abused" to also mean start and end of statements
    to enable proper rollback of statements and transactions. When LOCK
    TABLES has been issued the start_stmt method takes over the role of
    indicating start of statement but in this case there is no end of
    statement indicator(?).

    Called from lock.cc by lock_external() and unlock_external(). Also called
    from sql_table.cc by copy_data_between_tables().
*/

int ha_partition::external_lock(THD *thd, int lock_type)
{
  uint error;
  uint i, first_used_partition;
  MY_BITMAP *used_partitions;
  DBUG_ENTER("ha_partition::external_lock");

  DBUG_ASSERT(!auto_increment_lock && !auto_increment_safe_stmt_log_lock);
  
  if (lock_type == F_UNLCK)
    used_partitions= &m_locked_partitions;
  else
    used_partitions= &(m_part_info->lock_partitions);

  first_used_partition= bitmap_get_first_set(used_partitions);

  for (i= first_used_partition;
       i < m_tot_parts;
       i= bitmap_get_next_set(used_partitions, i))
  {
    DBUG_PRINT("info", ("external_lock(thd, %d) part %d", lock_type, i));
    if ((error= m_file[i]->ha_external_lock(thd, lock_type)))
    {
      if (lock_type != F_UNLCK)
        goto err_handler;
    }
    DBUG_PRINT("info", ("external_lock part %u lock %d", i, lock_type));
    if (lock_type != F_UNLCK)
      bitmap_set_bit(&m_locked_partitions, i);
  }
  if (lock_type == F_UNLCK)
  {
    bitmap_clear_all(used_partitions);
  }
  else
  {
    /* Add touched partitions to be included in reset(). */
    bitmap_union(&m_partitions_to_reset, used_partitions);
  }

  if (m_added_file && m_added_file[0])
  {
    handler **file= m_added_file;
    DBUG_ASSERT(lock_type == F_UNLCK);
    do
    {
      (void) (*file)->ha_external_lock(thd, lock_type);
    } while (*(++file));
  }
  DBUG_RETURN(0);

err_handler:
  uint j;
  for (j= first_used_partition;
       j < i;
       j= bitmap_get_next_set(&m_locked_partitions, j))
  {
    (void) m_file[j]->ha_external_lock(thd, F_UNLCK);
  }
  bitmap_clear_all(&m_locked_partitions);
  DBUG_RETURN(error);
}


/*
  Get the lock(s) for the table and perform conversion of locks if needed

  SYNOPSIS
    store_lock()
    thd                   Thread object
    to                    Lock object array
    lock_type             Table lock type

  RETURN VALUE
    >0                   Error code
    0                    Success

  DESCRIPTION
    The idea with handler::store_lock() is the following:

    The statement decided which locks we should need for the table
    for updates/deletes/inserts we get WRITE locks, for SELECT... we get
    read locks.

    Before adding the lock into the table lock handler (see thr_lock.c)
    mysqld calls store lock with the requested locks.  Store lock can now
    modify a write lock to a read lock (or some other lock), ignore the
    lock (if we don't want to use MySQL table locks at all) or add locks
    for many tables (like we do when we are using a MERGE handler).

    Berkeley DB for partition  changes all WRITE locks to TL_WRITE_ALLOW_WRITE
    (which signals that we are doing WRITES, but we are still allowing other
    reader's and writer's.

    When releasing locks, store_lock() is also called. In this case one
    usually doesn't have to do anything.

    store_lock is called when holding a global mutex to ensure that only
    one thread at a time changes the locking information of tables.

    In some exceptional cases MySQL may send a request for a TL_IGNORE;
    This means that we are requesting the same lock as last time and this
    should also be ignored. (This may happen when someone does a flush
    table when we have opened a part of the tables, in which case mysqld
    closes and reopens the tables and tries to get the same locks as last
    time).  In the future we will probably try to remove this.

    Called from lock.cc by get_lock_data().
*/

THR_LOCK_DATA **ha_partition::store_lock(THD *thd,
                                         THR_LOCK_DATA **to,
                                         enum thr_lock_type lock_type)
{
  uint i;
  DBUG_ENTER("ha_partition::store_lock");
  DBUG_ASSERT(thd == current_thd);

  /*
    This can be called from get_lock_data() in mysql_lock_abort_for_thread(),
    even when thd != table->in_use. In that case don't use partition pruning,
    but use all partitions instead to avoid using another threads structures.
  */
  if (thd != table->in_use)
  {
    for (i= 0; i < m_tot_parts; i++)
      to= m_file[i]->store_lock(thd, to, lock_type);
  }
  else
  {
    for (i= bitmap_get_first_set(&(m_part_info->lock_partitions));
         i < m_tot_parts;
         i= bitmap_get_next_set(&m_part_info->lock_partitions, i))
    {
      DBUG_PRINT("info", ("store lock %d iteration", i));
      to= m_file[i]->store_lock(thd, to, lock_type);
    }
  }
  DBUG_RETURN(to);
}

/*
  Start a statement when table is locked

  SYNOPSIS
    start_stmt()
    thd                  Thread object
    lock_type            Type of external lock

  RETURN VALUE
    >0                   Error code
    0                    Success

  DESCRIPTION
    This method is called instead of external lock when the table is locked
    before the statement is executed.
*/

int ha_partition::start_stmt(THD *thd, thr_lock_type lock_type)
{
  int error= 0;
  uint i;
  /* Assert that read_partitions is included in lock_partitions */
  DBUG_ASSERT(bitmap_is_subset(&m_part_info->read_partitions,
                               &m_part_info->lock_partitions));
  /*
    m_locked_partitions is set in previous external_lock/LOCK TABLES.
    Current statement's lock requests must not include any partitions
    not previously locked.
  */
  DBUG_ASSERT(bitmap_is_subset(&m_part_info->lock_partitions,
                               &m_locked_partitions));
  DBUG_ENTER("ha_partition::start_stmt");

  for (i= bitmap_get_first_set(&(m_part_info->lock_partitions));
       i < m_tot_parts;
       i= bitmap_get_next_set(&m_part_info->lock_partitions, i))
  {
    if ((error= m_file[i]->start_stmt(thd, lock_type)))
      break;
    /* Add partition to be called in reset(). */
    bitmap_set_bit(&m_partitions_to_reset, i);
  }
  DBUG_RETURN(error);
}


uint ha_partition::lock_count() const
{
  DBUG_ENTER("ha_partition::lock_count");
  /*
    The caller want to know the upper bound, to allocate enough memory.
    There is no performance lost if we simply return maximum number locks
    needed, only some minor over allocation of memory in get_lock_data().

    Also notice that this may be called for another thread != table->in_use,
    when mysql_lock_abort_for_thread() is called. So this is more safe, then
    using number of partitions after pruning.
  */
  DBUG_RETURN(m_tot_parts * m_num_locks);
}


/*
  Unlock last accessed row

  SYNOPSIS
    unlock_row()

  RETURN VALUE
    NONE

  DESCRIPTION
    Record currently processed was not in the result set of the statement
    and is thus unlocked. Used for UPDATE and DELETE queries.
*/

void ha_partition::unlock_row()
{
  DBUG_ENTER("ha_partition::unlock_row");
  m_file[m_last_part]->unlock_row();
  DBUG_VOID_RETURN;
}

bool ha_partition::was_semi_consistent_read()
{
  DBUG_ENTER("ha_partition::was_semi_consistent_read");
  DBUG_ASSERT(m_last_part < m_tot_parts &&
              bitmap_is_set(&(m_part_info->read_partitions), m_last_part));
  DBUG_RETURN(m_file[m_last_part]->was_semi_consistent_read());
}

void ha_partition::try_semi_consistent_read(bool yes)
{
  uint i;
  DBUG_ENTER("ha_partition::try_semi_consistent_read");
  
  i= bitmap_get_first_set(&(m_part_info->read_partitions));
  DBUG_ASSERT(i != MY_BIT_NONE);
  for (;
       i < m_tot_parts;
       i= bitmap_get_next_set(&m_part_info->read_partitions, i))
  {
    m_file[i]->try_semi_consistent_read(yes);
  }
  DBUG_VOID_RETURN;
}


/****************************************************************************
                MODULE change record
****************************************************************************/

/*
  Insert a row to the table

  SYNOPSIS
    write_row()
    buf                        The row in MySQL Row Format

  RETURN VALUE
    >0                         Error code
    0                          Success

  DESCRIPTION
    write_row() inserts a row. buf() is a byte array of data, normally
    record[0].

    You can use the field information to extract the data from the native byte
    array type.

    Example of this would be:
    for (Field **field=table->field ; *field ; field++)
    {
      ...
    }

    See ha_tina.cc for a variant of extracting all of the data as strings.
    ha_berkeley.cc has a variant of how to store it intact by "packing" it
    for ha_berkeley's own native storage type.

    Called from item_sum.cc, item_sum.cc, sql_acl.cc, sql_insert.cc,
    sql_insert.cc, sql_select.cc, sql_table.cc, sql_udf.cc, and sql_update.cc.

*/

int ha_partition::write_row(uchar * buf)
{
  uint32 part_id;
  int error;
  longlong func_value;
  bool have_auto_increment= table->next_number_field && buf == table->record[0];
  my_bitmap_map *old_map;
  THD *thd= ha_thd();
  sql_mode_t saved_sql_mode= thd->variables.sql_mode;
  bool saved_auto_inc_field_not_null= table->auto_increment_field_not_null;
  DBUG_ENTER("ha_partition::write_row");
  DBUG_ASSERT(buf == m_rec0);

  /*
    If we have an auto_increment column and we are writing a changed row
    or a new row, then update the auto_increment value in the record.
  */
  if (have_auto_increment)
  {
    if (!part_share->auto_inc_initialized &&
        !table_share->next_number_keypart)
    {
      /*
        If auto_increment in table_share is not initialized, start by
        initializing it.
      */
      info(HA_STATUS_AUTO);
    }
    error= update_auto_increment();

    /*
      If we have failed to set the auto-increment value for this row,
      it is highly likely that we will not be able to insert it into
      the correct partition. We must check and fail if neccessary.
    */
    if (error)
      goto exit;

    /*
      Don't allow generation of auto_increment value the partitions handler.
      If a partitions handler would change the value, then it might not
      match the partition any longer.
      This can occur if 'SET INSERT_ID = 0; INSERT (NULL)',
      So allow this by adding 'MODE_NO_AUTO_VALUE_ON_ZERO' to sql_mode.
      The partitions handler::next_insert_id must always be 0. Otherwise
      we need to forward release_auto_increment, or reset it for all
      partitions.
    */
    if (table->next_number_field->val_int() == 0)
    {
      table->auto_increment_field_not_null= TRUE;
      thd->variables.sql_mode|= MODE_NO_AUTO_VALUE_ON_ZERO;
    }
  }

  old_map= dbug_tmp_use_all_columns(table, table->read_set);
  error= m_part_info->get_partition_id(m_part_info, &part_id, &func_value);
  dbug_tmp_restore_column_map(table->read_set, old_map);
  if (unlikely(error))
  {
    m_part_info->err_value= func_value;
    goto exit;
  }
  if (!bitmap_is_set(&(m_part_info->lock_partitions), part_id))
  {
    DBUG_PRINT("info", ("Write to non-locked partition %u (func_value: %ld)",
                        part_id, (long) func_value));
    error= HA_ERR_NOT_IN_LOCK_PARTITIONS;
    goto exit;
  }
  m_last_part= part_id;
  DBUG_PRINT("info", ("Insert in partition %d", part_id));
  start_part_bulk_insert(thd, part_id);

  tmp_disable_binlog(thd); /* Do not replicate the low-level changes. */
  error= m_file[part_id]->ha_write_row(buf);
  if (have_auto_increment && !table->s->next_number_keypart)
    set_auto_increment_if_higher(table->next_number_field);
  reenable_binlog(thd);
exit:
  thd->variables.sql_mode= saved_sql_mode;
  table->auto_increment_field_not_null= saved_auto_inc_field_not_null;
  DBUG_RETURN(error);
}


/*
  Update an existing row

  SYNOPSIS
    update_row()
    old_data                 Old record in MySQL Row Format
    new_data                 New record in MySQL Row Format

  RETURN VALUE
    >0                         Error code
    0                          Success

  DESCRIPTION
    Yes, update_row() does what you expect, it updates a row. old_data will
    have the previous row record in it, while new_data will have the newest
    data in it.
    Keep in mind that the server can do updates based on ordering if an
    ORDER BY clause was used. Consecutive ordering is not guarenteed.

    Called from sql_select.cc, sql_acl.cc, sql_update.cc, and sql_insert.cc.
    new_data is always record[0]
    old_data is always record[1]
*/

int ha_partition::update_row(const uchar *old_data, uchar *new_data)
{
  THD *thd= ha_thd();
  uint32 new_part_id, old_part_id;
  int error= 0;
  longlong func_value;
  DBUG_ENTER("ha_partition::update_row");
  m_err_rec= NULL;

  // Need to read partition-related columns, to locate the row's partition:
  DBUG_ASSERT(bitmap_is_subset(&m_part_info->full_part_field_set,
                               table->read_set));
  if ((error= get_parts_for_update(old_data, new_data, table->record[0],
                                   m_part_info, &old_part_id, &new_part_id,
                                   &func_value)))
  {
    m_part_info->err_value= func_value;
    goto exit;
  }
  DBUG_ASSERT(bitmap_is_set(&(m_part_info->read_partitions), old_part_id));
  if (!bitmap_is_set(&(m_part_info->lock_partitions), new_part_id))
  {
    error= HA_ERR_NOT_IN_LOCK_PARTITIONS;
    goto exit;
  }

  /*
    The protocol for updating a row is:
    1) position the handler (cursor) on the row to be updated,
       either through the last read row (rnd or index) or by rnd_pos.
    2) call update_row with both old and new full records as arguments.

    This means that m_last_part should already be set to actual partition
    where the row was read from. And if that is not the same as the
    calculated part_id we found a misplaced row, we return an error to
    notify the user that something is broken in the row distribution
    between partitions! Since we don't check all rows on read, we return an
    error instead of correcting m_last_part, to make the user aware of the
    problem!

    Notice that HA_READ_BEFORE_WRITE_REMOVAL does not require this protocol,
    so this is not supported for this engine.
  */
  if (old_part_id != m_last_part)
  {
    m_err_rec= old_data;
    DBUG_RETURN(HA_ERR_ROW_IN_WRONG_PARTITION);
  }

  m_last_part= new_part_id;
  start_part_bulk_insert(thd, new_part_id);
  if (new_part_id == old_part_id)
  {
    DBUG_PRINT("info", ("Update in partition %d", new_part_id));
    tmp_disable_binlog(thd); /* Do not replicate the low-level changes. */
    error= m_file[new_part_id]->ha_update_row(old_data, new_data);
    reenable_binlog(thd);
    goto exit;
  }
  else
  {
    Field *saved_next_number_field= table->next_number_field;
    /*
      Don't allow generation of auto_increment value for update.
      table->next_number_field is never set on UPDATE.
      But is set for INSERT ... ON DUPLICATE KEY UPDATE,
      and since update_row() does not generate or update an auto_inc value,
      we cannot have next_number_field set when moving a row
      to another partition with write_row(), since that could
      generate/update the auto_inc value.
      This gives the same behavior for partitioned vs non partitioned tables.
    */
    table->next_number_field= NULL;
    DBUG_PRINT("info", ("Update from partition %d to partition %d",
                        old_part_id, new_part_id));
    tmp_disable_binlog(thd); /* Do not replicate the low-level changes. */
    error= m_file[new_part_id]->ha_write_row(new_data);
    reenable_binlog(thd);
    table->next_number_field= saved_next_number_field;
    if (error)
      goto exit;

    tmp_disable_binlog(thd); /* Do not replicate the low-level changes. */
    error= m_file[old_part_id]->ha_delete_row(old_data);
    reenable_binlog(thd);
    if (error)
    {
#ifdef IN_THE_FUTURE
      (void) m_file[new_part_id]->delete_last_inserted_row(new_data);
#endif
      goto exit;
    }
  }

exit:
  /*
    if updating an auto_increment column, update
    part_share->next_auto_inc_val if needed.
    (not to be used if auto_increment on secondary field in a multi-column
    index)
    mysql_update does not set table->next_number_field, so we use
    table->found_next_number_field instead.
    Also checking that the field is marked in the write set.
  */
  if (table->found_next_number_field &&
      new_data == table->record[0] &&
      !table->s->next_number_keypart &&
      bitmap_is_set(table->write_set,
                    table->found_next_number_field->field_index))
  {
    if (!part_share->auto_inc_initialized)
      info(HA_STATUS_AUTO);
    set_auto_increment_if_higher(table->found_next_number_field);
  }
  DBUG_RETURN(error);
}


/*
  Remove an existing row

  SYNOPSIS
    delete_row
    buf                      Deleted row in MySQL Row Format

  RETURN VALUE
    >0                       Error Code
    0                        Success

  DESCRIPTION
    This will delete a row. buf will contain a copy of the row to be deleted.
    The server will call this right after the current row has been read
    (from either a previous rnd_xxx() or index_xxx() call).
    If you keep a pointer to the last row or can access a primary key it will
    make doing the deletion quite a bit easier.
    Keep in mind that the server does no guarentee consecutive deletions.
    ORDER BY clauses can be used.

    Called in sql_acl.cc and sql_udf.cc to manage internal table information.
    Called in sql_delete.cc, sql_insert.cc, and sql_select.cc. In sql_select
    it is used for removing duplicates while in insert it is used for REPLACE
    calls.

    buf is either record[0] or record[1]
*/

int ha_partition::delete_row(const uchar *buf)
{
  uint32 part_id;
  int error;
  THD *thd= ha_thd();
  DBUG_ENTER("ha_partition::delete_row");
  m_err_rec= NULL;

  DBUG_ASSERT(bitmap_is_subset(&m_part_info->full_part_field_set,
                               table->read_set));
  if ((error= get_part_for_delete(buf, m_rec0, m_part_info, &part_id)))
  {
    DBUG_RETURN(error);
  }
  /* Should never call delete_row on a partition which is not read */
  DBUG_ASSERT(bitmap_is_set(&(m_part_info->read_partitions), part_id));
  DBUG_ASSERT(bitmap_is_set(&(m_part_info->lock_partitions), part_id));
  if (!bitmap_is_set(&(m_part_info->lock_partitions), part_id))
    DBUG_RETURN(HA_ERR_NOT_IN_LOCK_PARTITIONS);

  /*
    The protocol for deleting a row is:
    1) position the handler (cursor) on the row to be deleted,
       either through the last read row (rnd or index) or by rnd_pos.
    2) call delete_row with the full record as argument.

    This means that m_last_part should already be set to actual partition
    where the row was read from. And if that is not the same as the
    calculated part_id we found a misplaced row, we return an error to
    notify the user that something is broken in the row distribution
    between partitions! Since we don't check all rows on read, we return an
    error instead of forwarding the delete to the correct (m_last_part)
    partition!

    Notice that HA_READ_BEFORE_WRITE_REMOVAL does not require this protocol,
    so this is not supported for this engine.

    TODO: change the assert in InnoDB into an error instead and make this one
    an assert instead and remove the get_part_for_delete()!
  */
  if (part_id != m_last_part)
  {
    m_err_rec= buf;
    DBUG_RETURN(HA_ERR_ROW_IN_WRONG_PARTITION);
  }

  m_last_part= part_id;
  tmp_disable_binlog(thd);
  error= m_file[part_id]->ha_delete_row(buf);
  reenable_binlog(thd);
  DBUG_RETURN(error);
}


/*
  Delete all rows in a table

  SYNOPSIS
    delete_all_rows()

  RETURN VALUE
    >0                       Error Code
    0                        Success

  DESCRIPTION
    Used to delete all rows in a table. Both for cases of truncate and
    for cases where the optimizer realizes that all rows will be
    removed as a result of a SQL statement.

    Called from item_sum.cc by Item_func_group_concat::clear(),
    Item_sum_count_distinct::clear(), and Item_func_group_concat::clear().
    Called from sql_delete.cc by mysql_delete().
    Called from sql_select.cc by JOIN::reset().
    Called from sql_union.cc by st_select_lex_unit::exec().
*/

int ha_partition::delete_all_rows()
{
  int error;
  uint i;
  DBUG_ENTER("ha_partition::delete_all_rows");

  for (i= bitmap_get_first_set(&m_part_info->read_partitions);
       i < m_tot_parts;
       i= bitmap_get_next_set(&m_part_info->read_partitions, i))
  {
    /* Can be pruned, like DELETE FROM t PARTITION (pX) */
    if ((error= m_file[i]->ha_delete_all_rows()))
      DBUG_RETURN(error);
  }
  DBUG_RETURN(0);
}


int ha_partition::truncate()
{
  int error;
  handler **file;
  DBUG_ENTER("ha_partition::truncate");

  /*
    TRUNCATE also means resetting auto_increment. Hence, reset
    it so that it will be initialized again at the next use.
  */
  lock_auto_increment();
  part_share->next_auto_inc_val= 0;
  part_share->auto_inc_initialized= false;
  unlock_auto_increment();

  file= m_file;
  do
  {
    if ((error= (*file)->ha_truncate()))
      DBUG_RETURN(error);
  } while (*(++file));
  DBUG_RETURN(0);
}


int ha_partition::truncate_partition(Alter_info *alter_info, bool *binlog_stmt)
{
  int error= 0;
  List_iterator<partition_element> part_it(m_part_info->partitions);
  uint num_parts= m_part_info->num_parts;
  uint num_subparts= m_part_info->num_subparts;
  uint i= 0;
  DBUG_ENTER("ha_partition::truncate_partition");

  /* Only binlog when it starts any call to the partitions handlers */
  *binlog_stmt= false;

  if (set_part_state(alter_info, m_part_info, PART_ADMIN))
    DBUG_RETURN(HA_ERR_NO_PARTITION_FOUND);

  /*
    TRUNCATE also means resetting auto_increment. Hence, reset
    it so that it will be initialized again at the next use.
  */
  lock_auto_increment();
  part_share->next_auto_inc_val= 0;
  part_share->auto_inc_initialized= FALSE;
  unlock_auto_increment();

  *binlog_stmt= true;

  do
  {
    partition_element *part_elem= part_it++;
    if (part_elem->part_state == PART_ADMIN)
    {
      if (m_is_sub_partitioned)
      {
        List_iterator<partition_element>
                                    subpart_it(part_elem->subpartitions);
        partition_element *sub_elem;
        uint j= 0, part;
        do
        {
          sub_elem= subpart_it++;
          part= i * num_subparts + j;
          DBUG_PRINT("info", ("truncate subpartition %u (%s)",
                              part, sub_elem->partition_name));
          if ((error= m_file[part]->ha_truncate()))
            break;
          sub_elem->part_state= PART_NORMAL;
        } while (++j < num_subparts);
      }
      else
      {
        DBUG_PRINT("info", ("truncate partition %u (%s)", i,
                            part_elem->partition_name));
        error= m_file[i]->ha_truncate();
      }
      part_elem->part_state= PART_NORMAL;
    }
  } while (!error && (++i < num_parts));
  DBUG_RETURN(error);
}


/*
  Start a large batch of insert rows

  SYNOPSIS
    start_bulk_insert()
    rows                  Number of rows to insert

  RETURN VALUE
    NONE

  DESCRIPTION
    rows == 0 means we will probably insert many rows
*/
void ha_partition::start_bulk_insert(ha_rows rows)
{
  DBUG_ENTER("ha_partition::start_bulk_insert");

  m_bulk_inserted_rows= 0;
  bitmap_clear_all(&m_bulk_insert_started);
  /* use the last bit for marking if bulk_insert_started was called */
  bitmap_set_bit(&m_bulk_insert_started, m_tot_parts);
  DBUG_VOID_RETURN;
}


/*
  Check if start_bulk_insert has been called for this partition,
  if not, call it and mark it called
*/
void ha_partition::start_part_bulk_insert(THD *thd, uint part_id)
{
  long old_buffer_size;
  if (!bitmap_is_set(&m_bulk_insert_started, part_id) &&
      bitmap_is_set(&m_bulk_insert_started, m_tot_parts))
  {
    DBUG_ASSERT(bitmap_is_set(&(m_part_info->lock_partitions), part_id));
    old_buffer_size= thd->variables.read_buff_size;
    /* Update read_buffer_size for this partition */
    thd->variables.read_buff_size= estimate_read_buffer_size(old_buffer_size);
    m_file[part_id]->ha_start_bulk_insert(guess_bulk_insert_rows());
    bitmap_set_bit(&m_bulk_insert_started, part_id);
    thd->variables.read_buff_size= old_buffer_size;
  }
  m_bulk_inserted_rows++;
}

/*
  Estimate the read buffer size for each partition.
  SYNOPSIS
    ha_partition::estimate_read_buffer_size()
    original_size  read buffer size originally set for the server
  RETURN VALUE
    estimated buffer size.
  DESCRIPTION
    If the estimated number of rows to insert is less than 10 (but not 0)
    the new buffer size is same as original buffer size.
    In case of first partition of when partition function is monotonic 
    new buffer size is same as the original buffer size.
    For rest of the partition total buffer of 10*original_size is divided 
    equally if number of partition is more than 10 other wise each partition
    will be allowed to use original buffer size.
*/
long ha_partition::estimate_read_buffer_size(long original_size)
{
  /*
    If number of rows to insert is less than 10, but not 0,
    return original buffer size.
  */
  if (estimation_rows_to_insert && (estimation_rows_to_insert < 10))
    return (original_size);
  /*
    If first insert/partition and monotonic partition function,
    allow using buffer size originally set.
   */
  if (!m_bulk_inserted_rows &&
      m_part_func_monotonicity_info != NON_MONOTONIC &&
      m_tot_parts > 1)
    return original_size;
  /*
    Allow total buffer used in all partition to go up to 10*read_buffer_size.
    11*read_buffer_size in case of monotonic partition function.
  */

  if (m_tot_parts < 10)
      return original_size;
  return (original_size * 10 / m_tot_parts);
}

/*
  Try to predict the number of inserts into this partition.

  If less than 10 rows (including 0 which means Unknown)
    just give that as a guess
  If monotonic partitioning function was used
    guess that 50 % of the inserts goes to the first partition
  For all other cases, guess on equal distribution between the partitions
*/ 
ha_rows ha_partition::guess_bulk_insert_rows()
{
  DBUG_ENTER("guess_bulk_insert_rows");

  if (estimation_rows_to_insert < 10)
    DBUG_RETURN(estimation_rows_to_insert);

  /* If first insert/partition and monotonic partition function, guess 50%.  */
  if (!m_bulk_inserted_rows && 
      m_part_func_monotonicity_info != NON_MONOTONIC &&
      m_tot_parts > 1)
    DBUG_RETURN(estimation_rows_to_insert / 2);

  /* Else guess on equal distribution (+1 is to avoid returning 0/Unknown) */
  if (m_bulk_inserted_rows < estimation_rows_to_insert)
    DBUG_RETURN(((estimation_rows_to_insert - m_bulk_inserted_rows)
                / m_tot_parts) + 1);
  /* The estimation was wrong, must say 'Unknown' */
  DBUG_RETURN(0);
}


int ha_partition::end_bulk_insert()
{
  int error= 0;
  uint i;
  DBUG_ENTER("ha_partition::end_bulk_insert");

  if (!bitmap_is_set(&m_bulk_insert_started, m_tot_parts))
  {
    DBUG_ASSERT(0);
    DBUG_RETURN(error);
  }

  for (i= bitmap_get_first_set(&m_bulk_insert_started);
       i < m_tot_parts;
       i= bitmap_get_next_set(&m_bulk_insert_started, i))
  {
    int tmp;
    if ((tmp= m_file[i]->ha_end_bulk_insert()))
      error= tmp;
  }
  bitmap_clear_all(&m_bulk_insert_started);
  DBUG_RETURN(error);
}


/****************************************************************************
                MODULE full table scan
****************************************************************************/
/*
  Initialize engine for random reads

  SYNOPSIS
    ha_partition::rnd_init()
    scan        0  Initialize for random reads through rnd_pos()
                1  Initialize for random scan through rnd_next()

  RETURN VALUE
    >0          Error code
    0           Success

  DESCRIPTION 
    rnd_init() is called when the server wants the storage engine to do a
    table scan or when the server wants to access data through rnd_pos.

    When scan is used we will scan one handler partition at a time.
    When preparing for rnd_pos we will init all handler partitions.
    No extra cache handling is needed when scannning is not performed.

    Before initialising we will call rnd_end to ensure that we clean up from
    any previous incarnation of a table scan.
    Called from filesort.cc, records.cc, sql_handler.cc, sql_select.cc,
    sql_table.cc, and sql_update.cc.
*/

int ha_partition::rnd_init(bool scan)
{
  int error;
  uint i= 0;
  uint32 part_id;
  DBUG_ENTER("ha_partition::rnd_init");

  /*
    For operations that may need to change data, we may need to extend
    read_set.
  */
  if (get_lock_type() == F_WRLCK)
  {
    /*
      If write_set contains any of the fields used in partition and
      subpartition expression, we need to set all bits in read_set because
      the row may need to be inserted in a different [sub]partition. In
      other words update_row() can be converted into write_row(), which
      requires a complete record.
    */
    if (bitmap_is_overlapping(&m_part_info->full_part_field_set,
                              table->write_set))
      bitmap_set_all(table->read_set);
    else
    {
      /*
        Some handlers only read fields as specified by the bitmap for the
        read set. For partitioned handlers we always require that the
        fields of the partition functions are read such that we can
        calculate the partition id to place updated and deleted records.
      */
      bitmap_union(table->read_set, &m_part_info->full_part_field_set);
    }
  }

  /* Now we see what the index of our first important partition is */
  DBUG_PRINT("info", ("m_part_info->read_partitions: 0x%lx",
                      (long) m_part_info->read_partitions.bitmap));
  part_id= bitmap_get_first_set(&(m_part_info->read_partitions));
  DBUG_PRINT("info", ("m_part_spec.start_part %d", part_id));

  if (MY_BIT_NONE == part_id)
  {
    error= 0;
    goto err1;
  }

  /*
    We have a partition and we are scanning with rnd_next
    so we bump our cache
  */
  DBUG_PRINT("info", ("rnd_init on partition %d", part_id));
  if (scan)
  {
    /*
      rnd_end() is needed for partitioning to reset internal data if scan
      is already in use
    */
    rnd_end();
    late_extra_cache(part_id);
    if ((error= m_file[part_id]->ha_rnd_init(scan)))
      goto err;
  }
  else
  {
    for (i= part_id;
         i < m_tot_parts;
         i= bitmap_get_next_set(&m_part_info->read_partitions, i))
    {
      if ((error= m_file[i]->ha_rnd_init(scan)))
        goto err;
    }
  }
  m_scan_value= scan;
  m_part_spec.start_part= part_id;
  m_part_spec.end_part= m_tot_parts - 1;
  DBUG_PRINT("info", ("m_scan_value=%d", m_scan_value));
  DBUG_RETURN(0);

err:
  /* Call rnd_end for all previously inited partitions. */
  for (;
       part_id < i;
       part_id= bitmap_get_next_set(&m_part_info->read_partitions, part_id))
  {
    m_file[part_id]->ha_rnd_end();
  }
err1:
  m_scan_value= 2;
  m_part_spec.start_part= NO_CURRENT_PART_ID;
  DBUG_RETURN(error);
}


/*
  End of a table scan

  SYNOPSIS
    rnd_end()

  RETURN VALUE
    >0          Error code
    0           Success
*/

int ha_partition::rnd_end()
{
  DBUG_ENTER("ha_partition::rnd_end");
  switch (m_scan_value) {
  case 2:                                       // Error
    break;
  case 1:
    if (NO_CURRENT_PART_ID != m_part_spec.start_part)         // Table scan
    {
      late_extra_no_cache(m_part_spec.start_part);
      m_file[m_part_spec.start_part]->ha_rnd_end();
    }
    break;
  case 0:
    uint i;
    for (i= bitmap_get_first_set(&m_part_info->read_partitions);
         i < m_tot_parts;
         i= bitmap_get_next_set(&m_part_info->read_partitions, i))
    {
      m_file[i]->ha_rnd_end();
    }
    break;
  }
  m_scan_value= 2;
  m_part_spec.start_part= NO_CURRENT_PART_ID;
  DBUG_RETURN(0);
}

/*
  read next row during full table scan (scan in random row order)

  SYNOPSIS
    rnd_next()
    buf         buffer that should be filled with data

  RETURN VALUE
    >0          Error code
    0           Success

  DESCRIPTION
    This is called for each row of the table scan. When you run out of records
    you should return HA_ERR_END_OF_FILE.
    The Field structure for the table is the key to getting data into buf
    in a manner that will allow the server to understand it.

    Called from filesort.cc, records.cc, sql_handler.cc, sql_select.cc,
    sql_table.cc, and sql_update.cc.
*/

int ha_partition::rnd_next(uchar *buf)
{
  handler *file;
  int result= HA_ERR_END_OF_FILE;
  uint part_id= m_part_spec.start_part;
  DBUG_ENTER("ha_partition::rnd_next");

  if (NO_CURRENT_PART_ID == part_id)
  {
    /*
      The original set of partitions to scan was empty and thus we report
      the result here.
    */
    goto end;
  }
  
  DBUG_ASSERT(m_scan_value == 1);
  file= m_file[part_id];
  
  while (TRUE)
  {
    result= file->ha_rnd_next(buf);
    if (!result)
    {
      m_last_part= part_id;
      m_part_spec.start_part= part_id;
      table->status= 0;
      DBUG_RETURN(0);
    }

    /*
      if we get here, then the current partition ha_rnd_next returned failure
    */
    if (result == HA_ERR_RECORD_DELETED)
      continue;                               // Probably MyISAM

    if (result != HA_ERR_END_OF_FILE)
      goto end_dont_reset_start_part;         // Return error

    /* End current partition */
    late_extra_no_cache(part_id);
    DBUG_PRINT("info", ("rnd_end on partition %d", part_id));
    if ((result= file->ha_rnd_end()))
      break;
    
    /* Shift to next partition */
    part_id= bitmap_get_next_set(&m_part_info->read_partitions, part_id);
    if (part_id >= m_tot_parts)
    {
      result= HA_ERR_END_OF_FILE;
      break;
    }
    m_last_part= part_id;
    m_part_spec.start_part= part_id;
    file= m_file[part_id];
    DBUG_PRINT("info", ("rnd_init on partition %d", part_id));
    if ((result= file->ha_rnd_init(1)))
      break;
    late_extra_cache(part_id);
  }

end:
  m_part_spec.start_part= NO_CURRENT_PART_ID;
end_dont_reset_start_part:
  table->status= STATUS_NOT_FOUND;
  DBUG_RETURN(result);
}


/*
  Save position of current row

  SYNOPSIS
    position()
    record             Current record in MySQL Row Format

  RETURN VALUE
    NONE

  DESCRIPTION
    position() is called after each call to rnd_next() if the data needs
    to be ordered. You can do something like the following to store
    the position:
    ha_store_ptr(ref, ref_length, current_position);

    The server uses ref to store data. ref_length in the above case is
    the size needed to store current_position. ref is just a byte array
    that the server will maintain. If you are using offsets to mark rows, then
    current_position should be the offset. If it is a primary key like in
    BDB, then it needs to be a primary key.

    Called from filesort.cc, sql_select.cc, sql_delete.cc and sql_update.cc.
*/

void ha_partition::position(const uchar *record)
{
  handler *file= m_file[m_last_part];
  uint pad_length;
  DBUG_ASSERT(bitmap_is_set(&(m_part_info->read_partitions), m_last_part));
  DBUG_ENTER("ha_partition::position");

  file->position(record);
  int2store(ref, m_last_part);
  memcpy((ref + PARTITION_BYTES_IN_POS), file->ref, file->ref_length);
  pad_length= m_ref_length - PARTITION_BYTES_IN_POS - file->ref_length;
  if (pad_length)
    memset((ref + PARTITION_BYTES_IN_POS + file->ref_length), 0, pad_length);

  DBUG_VOID_RETURN;
}


/*
  Read row using position

  SYNOPSIS
    rnd_pos()
    out:buf                     Row read in MySQL Row Format
    position                    Position of read row

  RETURN VALUE
    >0                          Error code
    0                           Success

  DESCRIPTION
    This is like rnd_next, but you are given a position to use
    to determine the row. The position will be of the type that you stored in
    ref. You can use ha_get_ptr(pos,ref_length) to retrieve whatever key
    or position you saved when position() was called.
    Called from filesort.cc records.cc sql_insert.cc sql_select.cc
    sql_update.cc.
*/

int ha_partition::rnd_pos(uchar * buf, uchar *pos)
{
  uint part_id;
  handler *file;
  DBUG_ENTER("ha_partition::rnd_pos");

  part_id= uint2korr((const uchar *) pos);
  DBUG_ASSERT(part_id < m_tot_parts);
  file= m_file[part_id];
  DBUG_ASSERT(bitmap_is_set(&(m_part_info->read_partitions), part_id));
  m_last_part= part_id;
  DBUG_RETURN(file->ha_rnd_pos(buf, (pos + PARTITION_BYTES_IN_POS)));
}


/*
  Read row using position using given record to find

  SYNOPSIS
    rnd_pos_by_record()
    record             Current record in MySQL Row Format

  RETURN VALUE
    >0                 Error code
    0                  Success

  DESCRIPTION
    this works as position()+rnd_pos() functions, but does some extra work,
    calculating m_last_part - the partition to where the 'record'
    should go.

    called from replication (log_event.cc)
*/

int ha_partition::rnd_pos_by_record(uchar *record)
{
  DBUG_ENTER("ha_partition::rnd_pos_by_record");

  if (unlikely(get_part_for_delete(record, m_rec0, m_part_info, &m_last_part)))
    DBUG_RETURN(1);

  DBUG_RETURN(handler::rnd_pos_by_record(record));
}


/****************************************************************************
                MODULE index scan
****************************************************************************/
/*
  Positions an index cursor to the index specified in the handle. Fetches the
  row if available. If the key value is null, begin at the first key of the
  index.

  There are loads of optimisations possible here for the partition handler.
  The same optimisations can also be checked for full table scan although
  only through conditions and not from index ranges.
  Phase one optimisations:
    Check if the fields of the partition function are bound. If so only use
    the single partition it becomes bound to.
  Phase two optimisations:
    If it can be deducted through range or list partitioning that only a
    subset of the partitions are used, then only use those partitions.
*/


bool ha_partition::init_record_priority_queue()
{
  DBUG_ENTER("ha_partition::init_record_priority_queue");
  DBUG_ASSERT(!m_ordered_rec_buffer);
  /*
    Initialize the ordered record buffer.
  */
  if (!m_ordered_rec_buffer)
  {
    uint alloc_len;
    uint used_parts= bitmap_bits_set(&m_part_info->read_partitions);
    /* Allocate record buffer for each used partition. */
    alloc_len= used_parts * (m_rec_length + PARTITION_BYTES_IN_POS);
    /* Allocate a key for temporary use when setting up the scan. */
    alloc_len+= table_share->max_key_length;

    if (!(m_ordered_rec_buffer= (uchar*)my_malloc(alloc_len, MYF(MY_WME))))
      DBUG_RETURN(true);

    /*
      We set-up one record per partition and each record has 2 bytes in
      front where the partition id is written. This is used by ordered
      index_read.
      We also set-up a reference to the first record for temporary use in
      setting up the scan.
    */
    char *ptr= (char*) m_ordered_rec_buffer;
    uint i;
    for (i= bitmap_get_first_set(&m_part_info->read_partitions);
         i < m_tot_parts;
         i= bitmap_get_next_set(&m_part_info->read_partitions, i))
    {
      DBUG_PRINT("info", ("init rec-buf for part %u", i));
      int2store(ptr, i);
      ptr+= m_rec_length + PARTITION_BYTES_IN_POS;
    }
    m_start_key.key= (const uchar*)ptr;
    /* Initialize priority queue, initialized to reading forward. */
    if (init_queue(&m_queue, used_parts, (uint) PARTITION_BYTES_IN_POS,
                   0, key_rec_cmp, (void*)m_curr_key_info))
    {
      my_free(m_ordered_rec_buffer);
      m_ordered_rec_buffer= NULL;
      DBUG_RETURN(true);
    }
  }
  DBUG_RETURN(false);
}


void ha_partition::destroy_record_priority_queue()
{
  DBUG_ENTER("ha_partition::destroy_record_priority_queue");
  if (m_ordered_rec_buffer)
  {
    delete_queue(&m_queue);
    my_free(m_ordered_rec_buffer);
    m_ordered_rec_buffer= NULL;
  }
  DBUG_VOID_RETURN;
}


/*
  Initialize handler before start of index scan

  SYNOPSIS
    index_init()
    inx                Index number
    sorted             Is rows to be returned in sorted order

  RETURN VALUE
    >0                 Error code
    0                  Success

  DESCRIPTION
    index_init is always called before starting index scans (except when
    starting through index_read_idx and using read_range variants).
*/

int ha_partition::index_init(uint inx, bool sorted)
{
  int error= 0;
  uint i;
  DBUG_ENTER("ha_partition::index_init");

  DBUG_PRINT("info", ("inx %u sorted %u", inx, sorted));
  active_index= inx;
  m_part_spec.start_part= NO_CURRENT_PART_ID;
  m_start_key.length= 0;
  m_ordered= sorted;
  m_curr_key_info[0]= table->key_info+inx;
  if (m_pkey_is_clustered && table->s->primary_key != MAX_KEY)
  {
    /*
      if PK is clustered, then the key cmp must use the pk to
      differentiate between equal key in given index.
    */
    DBUG_PRINT("info", ("Clustered pk, using pk as secondary cmp"));
    m_curr_key_info[1]= table->key_info+table->s->primary_key;
    m_curr_key_info[2]= NULL;
  }
  else
    m_curr_key_info[1]= NULL;

  if (init_record_priority_queue())
    DBUG_RETURN(HA_ERR_OUT_OF_MEM);

  /*
    Some handlers only read fields as specified by the bitmap for the
    read set. For partitioned handlers we always require that the
    fields of the partition functions are read such that we can
    calculate the partition id to place updated and deleted records.
    But this is required for operations that may need to change data only.
  */
  if (get_lock_type() == F_WRLCK)
    bitmap_union(table->read_set, &m_part_info->full_part_field_set);
  for (i= bitmap_get_first_set(&m_part_info->read_partitions);
       i < m_tot_parts;
       i= bitmap_get_next_set(&m_part_info->read_partitions, i))
  {
    if ((error= m_file[i]->ha_index_init(inx, sorted)))
      goto err;

    DBUG_EXECUTE_IF("ha_partition_fail_index_init", {
      i++;
      error= HA_ERR_NO_PARTITION_FOUND;
      goto err;
    });
  }
err:
  if (error)
  {
    /* End the previously initialized indexes. */
    uint j;
    for (j= bitmap_get_first_set(&m_part_info->read_partitions);
         j < i;
         j= bitmap_get_next_set(&m_part_info->read_partitions, j))
    {
      (void) m_file[j]->ha_index_end();
    }
  }
  DBUG_RETURN(error);
}


/*
  End of index scan

  SYNOPSIS
    index_end()

  RETURN VALUE
    >0                 Error code
    0                  Success

  DESCRIPTION
    index_end is called at the end of an index scan to clean up any
    things needed to clean up.
*/

int ha_partition::index_end()
{
  int error= 0;
  uint i;
  DBUG_ENTER("ha_partition::index_end");

  active_index= MAX_KEY;
  m_part_spec.start_part= NO_CURRENT_PART_ID;
  for (i= bitmap_get_first_set(&m_part_info->read_partitions);
       i < m_tot_parts;
       i= bitmap_get_next_set(&m_part_info->read_partitions, i))
  {
    int tmp;
    if ((tmp= m_file[i]->ha_index_end()))
      error= tmp;
  }
  destroy_record_priority_queue();
  DBUG_RETURN(error);
}


/*
  Read one record in an index scan and start an index scan

  SYNOPSIS
    index_read_map()
    buf                    Read row in MySQL Row Format
    key                    Key parts in consecutive order
    keypart_map            Which part of key is used
    find_flag              What type of key condition is used

  RETURN VALUE
    >0                 Error code
    0                  Success

  DESCRIPTION
    index_read_map starts a new index scan using a start key. The MySQL Server
    will check the end key on its own. Thus to function properly the
    partitioned handler need to ensure that it delivers records in the sort
    order of the MySQL Server.
    index_read_map can be restarted without calling index_end on the previous
    index scan and without calling index_init. In this case the index_read_map
    is on the same index as the previous index_scan. This is particularly
    used in conjuntion with multi read ranges.
*/

int ha_partition::index_read_map(uchar *buf, const uchar *key,
                                 key_part_map keypart_map,
                                 enum ha_rkey_function find_flag)
{
  DBUG_ENTER("ha_partition::index_read_map");
  end_range= 0;
  m_index_scan_type= partition_index_read;
  m_start_key.key= key;
  m_start_key.keypart_map= keypart_map;
  m_start_key.flag= find_flag;
  DBUG_RETURN(common_index_read(buf, TRUE));
}


int ha_partition::common_index_read(uchar *buf, bool have_start_key)
{
  int error;
  uint UNINIT_VAR(key_len); /* used if have_start_key==TRUE */
  bool reverse_order= FALSE;
  DBUG_ENTER("ha_partition::common_index_read");

  DBUG_PRINT("info", ("m_ordered %u m_ordered_scan_ong %u",
                      m_ordered, m_ordered_scan_ongoing));

  if (have_start_key)
  {
    m_start_key.length= key_len= calculate_key_len(table, active_index, 
                                                   m_start_key.key,
                                                   m_start_key.keypart_map);
    DBUG_PRINT("info", ("have_start_key map %lu find_flag %u len %u",
                        m_start_key.keypart_map, m_start_key.flag, key_len));
    DBUG_ASSERT(key_len);
  }
  if ((error= partition_scan_set_up(buf, have_start_key)))
  {
    DBUG_RETURN(error);
  }

  if (have_start_key && 
      (m_start_key.flag == HA_READ_PREFIX_LAST ||
       m_start_key.flag == HA_READ_PREFIX_LAST_OR_PREV ||
       m_start_key.flag == HA_READ_BEFORE_KEY))
  {
    reverse_order= TRUE;
    m_ordered_scan_ongoing= TRUE;
  }
  DBUG_PRINT("info", ("m_ordered %u m_o_scan_ong %u have_start_key %u",
                      m_ordered, m_ordered_scan_ongoing, have_start_key));
  if (!m_ordered_scan_ongoing)
   {
    /*
      We use unordered index scan when read_range is used and flag
      is set to not use ordered.
      We also use an unordered index scan when the number of partitions to
      scan is only one.
      The unordered index scan will use the partition set created.
    */
    DBUG_PRINT("info", ("doing unordered scan"));
    error= handle_unordered_scan_next_partition(buf);
  }
  else
  {
    /*
      In all other cases we will use the ordered index scan. This will use
      the partition set created by the get_partition_set method.
    */
    error= handle_ordered_index_scan(buf, reverse_order);
  }
  DBUG_RETURN(error);
}


/*
  Start an index scan from leftmost record and return first record

  SYNOPSIS
    index_first()
    buf                 Read row in MySQL Row Format

  RETURN VALUE
    >0                  Error code
    0                   Success

  DESCRIPTION
    index_first() asks for the first key in the index.
    This is similar to index_read except that there is no start key since
    the scan starts from the leftmost entry and proceeds forward with
    index_next.

    Called from opt_range.cc, opt_sum.cc, sql_handler.cc,
    and sql_select.cc.
*/

int ha_partition::index_first(uchar * buf)
{
  DBUG_ENTER("ha_partition::index_first");

  end_range= 0;
  m_index_scan_type= partition_index_first;
  DBUG_RETURN(common_first_last(buf));
}


/*
  Start an index scan from rightmost record and return first record
  
  SYNOPSIS
    index_last()
    buf                 Read row in MySQL Row Format

  RETURN VALUE
    >0                  Error code
    0                   Success

  DESCRIPTION
    index_last() asks for the last key in the index.
    This is similar to index_read except that there is no start key since
    the scan starts from the rightmost entry and proceeds forward with
    index_prev.

    Called from opt_range.cc, opt_sum.cc, sql_handler.cc,
    and sql_select.cc.
*/

int ha_partition::index_last(uchar * buf)
{
  DBUG_ENTER("ha_partition::index_last");

  m_index_scan_type= partition_index_last;
  DBUG_RETURN(common_first_last(buf));
}

/*
  Common routine for index_first/index_last

  SYNOPSIS
    ha_partition::common_first_last()
  
  see index_first for rest
*/

int ha_partition::common_first_last(uchar *buf)
{
  int error;

  if ((error= partition_scan_set_up(buf, FALSE)))
    return error;
  if (!m_ordered_scan_ongoing &&
      m_index_scan_type != partition_index_last)
    return handle_unordered_scan_next_partition(buf);
  return handle_ordered_index_scan(buf, FALSE);
}


/*
  Read last using key

  SYNOPSIS
    index_read_last_map()
    buf                   Read row in MySQL Row Format
    key                   Key
    keypart_map           Which part of key is used

  RETURN VALUE
    >0                    Error code
    0                     Success

  DESCRIPTION
    This is used in join_read_last_key to optimise away an ORDER BY.
    Can only be used on indexes supporting HA_READ_ORDER
*/

int ha_partition::index_read_last_map(uchar *buf, const uchar *key,
                                      key_part_map keypart_map)
{
  DBUG_ENTER("ha_partition::index_read_last_map");

  m_ordered= TRUE;                              // Safety measure
  end_range= 0;
  m_index_scan_type= partition_index_read_last;
  m_start_key.key= key;
  m_start_key.keypart_map= keypart_map;
  m_start_key.flag= HA_READ_PREFIX_LAST;
  DBUG_RETURN(common_index_read(buf, TRUE));
}


/*
  Optimization of the default implementation to take advantage of dynamic
  partition pruning.
*/
int ha_partition::index_read_idx_map(uchar *buf, uint index,
                                     const uchar *key,
                                     key_part_map keypart_map,
                                     enum ha_rkey_function find_flag)
{
  int error= HA_ERR_KEY_NOT_FOUND;
  DBUG_ENTER("ha_partition::index_read_idx_map");

  if (find_flag == HA_READ_KEY_EXACT)
  {
    uint part;
    m_start_key.key= key;
    m_start_key.keypart_map= keypart_map;
    m_start_key.flag= find_flag;
    m_start_key.length= calculate_key_len(table, index, m_start_key.key,
                                          m_start_key.keypart_map);

    get_partition_set(table, buf, index, &m_start_key, &m_part_spec);

    /* 
      We have either found exactly 1 partition
      (in which case start_part == end_part)
      or no matching partitions (start_part > end_part)
    */
    DBUG_ASSERT(m_part_spec.start_part >= m_part_spec.end_part);
    /* The start part is must be marked as used. */
    DBUG_ASSERT(m_part_spec.start_part > m_part_spec.end_part ||
                bitmap_is_set(&(m_part_info->read_partitions),
                              m_part_spec.start_part));

    for (part= m_part_spec.start_part;
         part <= m_part_spec.end_part;
         part= bitmap_get_next_set(&m_part_info->read_partitions, part))
    {
      error= m_file[part]->ha_index_read_idx_map(buf, index, key,
                                                 keypart_map, find_flag);
      if (error != HA_ERR_KEY_NOT_FOUND &&
          error != HA_ERR_END_OF_FILE)
        break;
    }
    if (part <= m_part_spec.end_part)
      m_last_part= part;
  }
  else
  {
    /*
      If not only used with READ_EXACT, we should investigate if possible
      to optimize for other find_flag's as well.
    */
    DBUG_ASSERT(0);
    /* fall back on the default implementation */
    error= handler::index_read_idx_map(buf, index, key, keypart_map, find_flag);
  }
  DBUG_RETURN(error);
}


/*
  Read next record in a forward index scan

  SYNOPSIS
    index_next()
    buf                   Read row in MySQL Row Format

  RETURN VALUE
    >0                    Error code
    0                     Success

  DESCRIPTION
    Used to read forward through the index.
*/

int ha_partition::index_next(uchar * buf)
{
  DBUG_ENTER("ha_partition::index_next");

  /*
    TODO(low priority):
    If we want partition to work with the HANDLER commands, we
    must be able to do index_last() -> index_prev() -> index_next()
    and if direction changes, we must step back those partitions in
    the record queue so we don't return a value from the wrong direction.
  */
  DBUG_ASSERT(m_index_scan_type != partition_index_last);
  if (!m_ordered_scan_ongoing)
  {
    DBUG_RETURN(handle_unordered_next(buf, FALSE));
  }
  DBUG_RETURN(handle_ordered_next(buf, FALSE));
}


/*
  Read next record special

  SYNOPSIS
    index_next_same()
    buf                   Read row in MySQL Row Format
    key                   Key
    keylen                Length of key

  RETURN VALUE
    >0                    Error code
    0                     Success

  DESCRIPTION
    This routine is used to read the next but only if the key is the same
    as supplied in the call.
*/

int ha_partition::index_next_same(uchar *buf, const uchar *key, uint keylen)
{
  DBUG_ENTER("ha_partition::index_next_same");

  DBUG_ASSERT(keylen == m_start_key.length);
  DBUG_ASSERT(m_index_scan_type != partition_index_last);
  if (!m_ordered_scan_ongoing)
    DBUG_RETURN(handle_unordered_next(buf, TRUE));
  DBUG_RETURN(handle_ordered_next(buf, TRUE));
}


/*
  Read next record when performing index scan backwards

  SYNOPSIS
    index_prev()
    buf                   Read row in MySQL Row Format

  RETURN VALUE
    >0                    Error code
    0                     Success

  DESCRIPTION
    Used to read backwards through the index.
*/

int ha_partition::index_prev(uchar * buf)
{
  DBUG_ENTER("ha_partition::index_prev");

  /* TODO: read comment in index_next */
  DBUG_ASSERT(m_index_scan_type != partition_index_first);
  DBUG_RETURN(handle_ordered_prev(buf));
}


/*
  Start a read of one range with start and end key

  SYNOPSIS
    read_range_first()
    start_key           Specification of start key
    end_key             Specification of end key
    eq_range_arg        Is it equal range
    sorted              Should records be returned in sorted order

  RETURN VALUE
    >0                    Error code
    0                     Success

  DESCRIPTION
    We reimplement read_range_first since we don't want the compare_key
    check at the end. This is already performed in the partition handler.
    read_range_next is very much different due to that we need to scan
    all underlying handlers.
*/

int ha_partition::read_range_first(const key_range *start_key,
                                   const key_range *end_key,
                                   bool eq_range_arg, bool sorted)
{
  int error;
  DBUG_ENTER("ha_partition::read_range_first");

  m_ordered= sorted;
  eq_range= eq_range_arg;
  set_end_range(end_key, RANGE_SCAN_ASC);

  range_key_part= m_curr_key_info[0]->key_part;
  if (start_key)
    m_start_key= *start_key;
  else
    m_start_key.key= NULL;

  m_index_scan_type= partition_read_range;
  error= common_index_read(m_rec0, test(start_key));
  DBUG_RETURN(error);
}


/*
  Read next record in read of a range with start and end key

  SYNOPSIS
    read_range_next()

  RETURN VALUE
    >0                    Error code
    0                     Success
*/

int ha_partition::read_range_next()
{
  DBUG_ENTER("ha_partition::read_range_next");

  if (m_ordered_scan_ongoing)
  {
    DBUG_RETURN(handle_ordered_next(table->record[0], eq_range));
  }
  DBUG_RETURN(handle_unordered_next(table->record[0], eq_range));
}


/*
  Common routine to set up index scans

  SYNOPSIS
    ha_partition::partition_scan_set_up()
      buf            Buffer to later return record in (this function
                     needs it to calculcate partitioning function
                     values)

      idx_read_flag  TRUE <=> m_start_key has range start endpoint which 
                     probably can be used to determine the set of partitions
                     to scan.
                     FALSE <=> there is no start endpoint.

  DESCRIPTION
    Find out which partitions we'll need to read when scanning the specified
    range.

    If we need to scan only one partition, set m_ordered_scan_ongoing=FALSE
    as we will not need to do merge ordering.

  RETURN VALUE
    >0                    Error code
    0                     Success
*/

int ha_partition::partition_scan_set_up(uchar * buf, bool idx_read_flag)
{
  DBUG_ENTER("ha_partition::partition_scan_set_up");

  if (idx_read_flag)
    get_partition_set(table,buf,active_index,&m_start_key,&m_part_spec);
  else
  {
    m_part_spec.start_part= 0;
    m_part_spec.end_part= m_tot_parts - 1;
  }
  if (m_part_spec.start_part > m_part_spec.end_part)
  {
    /*
      We discovered a partition set but the set was empty so we report
      key not found.
    */
    DBUG_PRINT("info", ("scan with no partition to scan"));
    table->status= STATUS_NOT_FOUND;
    DBUG_RETURN(HA_ERR_END_OF_FILE);
  }
  if (m_part_spec.start_part == m_part_spec.end_part)
  {
    /*
      We discovered a single partition to scan, this never needs to be
      performed using the ordered index scan.
    */
    DBUG_PRINT("info", ("index scan using the single partition %d",
                        m_part_spec.start_part));
    m_ordered_scan_ongoing= FALSE;
  }
  else
  {
    /*
      Set m_ordered_scan_ongoing according how the scan should be done
      Only exact partitions are discovered atm by get_partition_set.
      Verify this, also bitmap must have at least one bit set otherwise
      the result from this table is the empty set.
    */
    uint start_part= bitmap_get_first_set(&(m_part_info->read_partitions));
    if (start_part == MY_BIT_NONE)
    {
      DBUG_PRINT("info", ("scan with no partition to scan"));
      table->status= STATUS_NOT_FOUND;
      DBUG_RETURN(HA_ERR_END_OF_FILE);
    }
    if (start_part > m_part_spec.start_part)
      m_part_spec.start_part= start_part;
    DBUG_ASSERT(m_part_spec.start_part < m_tot_parts);
    m_ordered_scan_ongoing= m_ordered;
  }
  DBUG_ASSERT(m_part_spec.start_part < m_tot_parts &&
              m_part_spec.end_part < m_tot_parts);
  DBUG_RETURN(0);
}


/****************************************************************************
  Unordered Index Scan Routines
****************************************************************************/
/*
  Common routine to handle index_next with unordered results

  SYNOPSIS
    handle_unordered_next()
    out:buf                       Read row in MySQL Row Format
    next_same                     Called from index_next_same

  RETURN VALUE
    HA_ERR_END_OF_FILE            End of scan
    0                             Success
    other                         Error code

  DESCRIPTION
    These routines are used to scan partitions without considering order.
    This is performed in two situations.
    1) In read_multi_range this is the normal case
    2) When performing any type of index_read, index_first, index_last where
    all fields in the partition function is bound. In this case the index
    scan is performed on only one partition and thus it isn't necessary to
    perform any sort.
*/

int ha_partition::handle_unordered_next(uchar *buf, bool is_next_same)
{
  handler *file;
  int error;
  DBUG_ENTER("ha_partition::handle_unordered_next");

  if (m_part_spec.start_part >= m_tot_parts)
  {
    /* Should never happen! */
    DBUG_ASSERT(0);
    DBUG_RETURN(HA_ERR_END_OF_FILE);
  }
  file= m_file[m_part_spec.start_part];

  /*
    We should consider if this should be split into three functions as
    partition_read_range is_next_same are always local constants
  */

  if (m_index_scan_type == partition_read_range)
  {
    if (!(error= file->read_range_next()))
    {
      m_last_part= m_part_spec.start_part;
      DBUG_RETURN(0);
    }
  }
  else if (is_next_same)
  {
    if (!(error= file->ha_index_next_same(buf, m_start_key.key,
                                          m_start_key.length)))
    {
      m_last_part= m_part_spec.start_part;
      DBUG_RETURN(0);
    }
  }
  else 
  {
    if (!(error= file->ha_index_next(buf)))
    {
      m_last_part= m_part_spec.start_part;
      DBUG_RETURN(0);                           // Row was in range
    }
  }

  if (error == HA_ERR_END_OF_FILE)
  {
    m_part_spec.start_part++;                    // Start using next part
    error= handle_unordered_scan_next_partition(buf);
  }
  DBUG_RETURN(error);
}


/*
  Handle index_next when changing to new partition

  SYNOPSIS
    handle_unordered_scan_next_partition()
    buf                       Read row in MySQL Row Format

  RETURN VALUE
    HA_ERR_END_OF_FILE            End of scan
    0                             Success
    other                         Error code

  DESCRIPTION
    This routine is used to start the index scan on the next partition.
    Both initial start and after completing scan on one partition.
*/

int ha_partition::handle_unordered_scan_next_partition(uchar * buf)
{
  uint i= m_part_spec.start_part;
  int saved_error= HA_ERR_END_OF_FILE;
  DBUG_ENTER("ha_partition::handle_unordered_scan_next_partition");

  if (i)
    i= bitmap_get_next_set(&m_part_info->read_partitions, i - 1);
  else
    i= bitmap_get_first_set(&m_part_info->read_partitions);

  for (;
       i <= m_part_spec.end_part;
       i= bitmap_get_next_set(&m_part_info->read_partitions, i))
  {
    int error;
    handler *file= m_file[i];
    m_part_spec.start_part= i;
    switch (m_index_scan_type) {
    case partition_read_range:
      DBUG_PRINT("info", ("read_range_first on partition %d", i));
      error= file->read_range_first(m_start_key.key? &m_start_key: NULL,
                                    end_range, eq_range, FALSE);
      break;
    case partition_index_read:
      DBUG_PRINT("info", ("index_read on partition %d", i));
      error= file->ha_index_read_map(buf, m_start_key.key,
                                     m_start_key.keypart_map,
                                     m_start_key.flag);
      break;
    case partition_index_first:
      DBUG_PRINT("info", ("index_first on partition %d", i));
      error= file->ha_index_first(buf);
      break;
    case partition_index_first_unordered:
      /*
        We perform a scan without sorting and this means that we
        should not use the index_first since not all handlers
        support it and it is also unnecessary to restrict sort
        order.
      */
      DBUG_PRINT("info", ("read_range_first on partition %d", i));
      table->record[0]= buf;
      error= file->read_range_first(0, end_range, eq_range, 0);
      table->record[0]= m_rec0;
      break;
    default:
      DBUG_ASSERT(FALSE);
      DBUG_RETURN(1);
    }
    if (!error)
    {
      m_last_part= i;
      DBUG_RETURN(0);
    }
    if ((error != HA_ERR_END_OF_FILE) && (error != HA_ERR_KEY_NOT_FOUND))
      DBUG_RETURN(error);

    /*
      If HA_ERR_KEY_NOT_FOUND, we must return that error instead of 
      HA_ERR_END_OF_FILE, to be able to continue search.
    */
    if (saved_error != HA_ERR_KEY_NOT_FOUND)
      saved_error= error;
    DBUG_PRINT("info", ("END_OF_FILE/KEY_NOT_FOUND on partition %d", i));
  }
  if (saved_error == HA_ERR_END_OF_FILE)
    m_part_spec.start_part= NO_CURRENT_PART_ID;
  DBUG_RETURN(saved_error);
}


int ha_partition::handle_ordered_index_scan(uchar *buf, bool reverse_order)
{
  uint i;
  uint j= 0;
  bool found= FALSE;
  uchar *part_rec_buf_ptr= m_ordered_rec_buffer;
  int saved_error= HA_ERR_END_OF_FILE;
  DBUG_ENTER("ha_partition::handle_ordered_index_scan");

  if (m_key_not_found)
  {
    m_key_not_found= false;
    bitmap_clear_all(&m_key_not_found_partitions);
  }
  m_top_entry= NO_CURRENT_PART_ID;
  queue_remove_all(&m_queue);
  DBUG_ASSERT(bitmap_is_set(&m_part_info->read_partitions,
                            m_part_spec.start_part));

  /*
    Position part_rec_buf_ptr to point to the first used partition >=
    start_part. There may be partitions marked by used_partitions,
    but is before start_part. These partitions has allocated record buffers
    but is dynamically pruned, so those buffers must be skipped.
  */
  for (i= bitmap_get_first_set(&m_part_info->read_partitions);
       i < m_part_spec.start_part;
       i= bitmap_get_next_set(&m_part_info->read_partitions, i))
  {
    part_rec_buf_ptr+= m_rec_length + PARTITION_BYTES_IN_POS;
  }
  DBUG_PRINT("info", ("m_part_spec.start_part %u first_used_part %u",
                      m_part_spec.start_part, i));
  for (/* continue from above */ ;
       i <= m_part_spec.end_part;
       i= bitmap_get_next_set(&m_part_info->read_partitions, i))
  {
    DBUG_PRINT("info", ("reading from part %u (scan_type: %u)",
                        i, m_index_scan_type));
    DBUG_ASSERT(i == uint2korr(part_rec_buf_ptr));
    uchar *rec_buf_ptr= part_rec_buf_ptr + PARTITION_BYTES_IN_POS;
    int error;
    handler *file= m_file[i];

    switch (m_index_scan_type) {
    case partition_index_read:
      error= file->ha_index_read_map(rec_buf_ptr,
                                     m_start_key.key,
                                     m_start_key.keypart_map,
                                     m_start_key.flag);
      break;
    case partition_index_first:
      error= file->ha_index_first(rec_buf_ptr);
      reverse_order= FALSE;
      break;
    case partition_index_last:
      error= file->ha_index_last(rec_buf_ptr);
      reverse_order= TRUE;
      break;
    case partition_index_read_last:
      error= file->ha_index_read_last_map(rec_buf_ptr,
                                          m_start_key.key,
                                          m_start_key.keypart_map);
      reverse_order= TRUE;
      break;
    case partition_read_range:
    {
      /* 
        This can only read record to table->record[0], as it was set when
        the table was being opened. We have to memcpy data ourselves.
      */
      error= file->read_range_first(m_start_key.key? &m_start_key: NULL,
                                    end_range, eq_range, TRUE);
      memcpy(rec_buf_ptr, table->record[0], m_rec_length);
      reverse_order= FALSE;
      break;
    }
    default:
      DBUG_ASSERT(FALSE);
      DBUG_RETURN(HA_ERR_END_OF_FILE);
    }
    if (!error)
    {
      found= TRUE;
      /*
        Initialize queue without order first, simply insert
      */
      queue_element(&m_queue, j++)= part_rec_buf_ptr;
    }
    else if (error != HA_ERR_KEY_NOT_FOUND && error != HA_ERR_END_OF_FILE)
    {
      DBUG_RETURN(error);
    }
    else if (error == HA_ERR_KEY_NOT_FOUND)
    {
      DBUG_PRINT("info", ("HA_ERR_KEY_NOT_FOUND from partition %u", i));
      bitmap_set_bit(&m_key_not_found_partitions, i);
      m_key_not_found= true;
      saved_error= error;
    }
    part_rec_buf_ptr+= m_rec_length + PARTITION_BYTES_IN_POS;
  }
  if (found)
  {
    /*
      We found at least one partition with data, now sort all entries and
      after that read the first entry and copy it to the buffer to return in.
    */
    queue_set_max_at_top(&m_queue, reverse_order);
    queue_set_cmp_arg(&m_queue, (void*)m_curr_key_info);
    m_queue.elements= j;
    queue_fix(&m_queue);
    return_top_record(buf);
    table->status= 0;
    DBUG_PRINT("info", ("Record returned from partition %d", m_top_entry));
    DBUG_RETURN(0);
  }
  DBUG_RETURN(saved_error);
}


/*
  Return the top record in sort order

  SYNOPSIS
    return_top_record()
    out:buf                  Row returned in MySQL Row Format

  RETURN VALUE
    NONE
*/

void ha_partition::return_top_record(uchar *buf)
{
  uint part_id;
  uchar *key_buffer= queue_top(&m_queue);
  uchar *rec_buffer= key_buffer + PARTITION_BYTES_IN_POS;

  part_id= uint2korr(key_buffer);
  memcpy(buf, rec_buffer, m_rec_length);
  m_last_part= part_id;
  m_top_entry= part_id;
}


int ha_partition::handle_ordered_index_scan_key_not_found()
{
  int error;
  uint i;
  uchar *part_buf= m_ordered_rec_buffer;
  uchar *curr_rec_buf= NULL;
  DBUG_ENTER("ha_partition::handle_ordered_index_scan_key_not_found");
  DBUG_ASSERT(m_key_not_found);
  /*
    Loop over all used partitions to get the correct offset
    into m_ordered_rec_buffer.
  */
  for (i= bitmap_get_first_set(&m_part_info->read_partitions);
       i < m_tot_parts;
       i= bitmap_get_next_set(&m_part_info->read_partitions, i))
  {
    if (bitmap_is_set(&m_key_not_found_partitions, i))
    {
      /*
        This partition is used and did return HA_ERR_KEY_NOT_FOUND
        in index_read_map.
      */
      curr_rec_buf= part_buf + PARTITION_BYTES_IN_POS;
      error= m_file[i]->ha_index_next(curr_rec_buf);
      /* HA_ERR_KEY_NOT_FOUND is not allowed from index_next! */
      DBUG_ASSERT(error != HA_ERR_KEY_NOT_FOUND);
      if (!error)
        queue_insert(&m_queue, part_buf);
      else if (error != HA_ERR_END_OF_FILE && error != HA_ERR_KEY_NOT_FOUND)
        DBUG_RETURN(error);
    }
    part_buf+= m_rec_length + PARTITION_BYTES_IN_POS;
  }
  DBUG_ASSERT(curr_rec_buf);
  bitmap_clear_all(&m_key_not_found_partitions);
  m_key_not_found= false;

  /* Update m_top_entry, which may have changed. */
  uchar *key_buffer= queue_top(&m_queue);
  m_top_entry= uint2korr(key_buffer);
  DBUG_RETURN(0);
}


/*
  Common routine to handle index_next with ordered results

  SYNOPSIS
    handle_ordered_next()
    out:buf                       Read row in MySQL Row Format
    next_same                     Called from index_next_same

  RETURN VALUE
    HA_ERR_END_OF_FILE            End of scan
    0                             Success
    other                         Error code
*/

int ha_partition::handle_ordered_next(uchar *buf, bool is_next_same)
{
  int error;
  uint part_id= m_top_entry;
  uchar *rec_buf= queue_top(&m_queue) + PARTITION_BYTES_IN_POS;
  handler *file;
  DBUG_ENTER("ha_partition::handle_ordered_next");
  
  if (m_key_not_found)
  {
    if (is_next_same)
    {
      /* Only rows which match the key. */
      m_key_not_found= false;
      bitmap_clear_all(&m_key_not_found_partitions);
    }
    else
    {
      /* There are partitions not included in the index record queue. */
      uint old_elements= m_queue.elements;
      if ((error= handle_ordered_index_scan_key_not_found()))
        DBUG_RETURN(error);
      /*
        If the queue top changed, i.e. one of the partitions that gave
        HA_ERR_KEY_NOT_FOUND in index_read_map found the next record,
        return it.
        Otherwise replace the old with a call to index_next (fall through).
      */
      if (old_elements != m_queue.elements && part_id != m_top_entry)
      {
        return_top_record(buf);
        DBUG_RETURN(0);
      }
    }
  }
  if (part_id >= m_tot_parts)
    DBUG_RETURN(HA_ERR_END_OF_FILE);

  file= m_file[part_id];

  if (m_index_scan_type == partition_read_range)
  {
    error= file->read_range_next();
    memcpy(rec_buf, table->record[0], m_rec_length);
  }
  else if (!is_next_same)
    error= file->ha_index_next(rec_buf);
  else
    error= file->ha_index_next_same(rec_buf, m_start_key.key,
                                    m_start_key.length);
  if (error)
  {
    if (error == HA_ERR_END_OF_FILE)
    {
      /* Return next buffered row */
      queue_remove(&m_queue, (uint) 0);
      if (m_queue.elements)
      {
         DBUG_PRINT("info", ("Record returned from partition %u (2)",
                     m_top_entry));
         return_top_record(buf);
         table->status= 0;
         error= 0;
      }
    }
    DBUG_RETURN(error);
  }
  queue_replaced(&m_queue);
  return_top_record(buf);
  DBUG_PRINT("info", ("Record returned from partition %u", m_top_entry));
  DBUG_RETURN(0);
}


/*
  Common routine to handle index_prev with ordered results

  SYNOPSIS
    handle_ordered_prev()
    out:buf                       Read row in MySQL Row Format

  RETURN VALUE
    HA_ERR_END_OF_FILE            End of scan
    0                             Success
    other                         Error code
*/

int ha_partition::handle_ordered_prev(uchar *buf)
{
  int error;
  uint part_id= m_top_entry;
  uchar *rec_buf= queue_top(&m_queue) + PARTITION_BYTES_IN_POS;
  handler *file= m_file[part_id];
  DBUG_ENTER("ha_partition::handle_ordered_prev");

  if ((error= file->ha_index_prev(rec_buf)))
  {
    if (error == HA_ERR_END_OF_FILE)
    {
      queue_remove(&m_queue, (uint) 0);
      if (m_queue.elements)
      {
        return_top_record(buf);
        DBUG_PRINT("info", ("Record returned from partition %d (2)",
                            m_top_entry));
        error= 0;
        table->status= 0;
      }
    }
    DBUG_RETURN(error);
  }
  queue_replaced(&m_queue);
  return_top_record(buf);
  DBUG_PRINT("info", ("Record returned from partition %d", m_top_entry));
  DBUG_RETURN(0);
}


/****************************************************************************
                MODULE information calls
****************************************************************************/

/*
  These are all first approximations of the extra, info, scan_time
  and read_time calls
*/

int ha_partition::compare_number_of_records(ha_partition *me,
                                            const uint32 *a,
                                            const uint32 *b)
{
  handler **file= me->m_file;
  /* Note: sorting in descending order! */
  if (file[*a]->stats.records > file[*b]->stats.records)
    return -1;
  if (file[*a]->stats.records < file[*b]->stats.records)
    return 1;
  return 0;
}


/*
  General method to gather info from handler

  SYNOPSIS
    info()
    flag              Specifies what info is requested

  RETURN VALUE
    NONE

  DESCRIPTION
    ::info() is used to return information to the optimizer.
    Currently this table handler doesn't implement most of the fields
    really needed. SHOW also makes use of this data
    Another note, if your handler doesn't proved exact record count,
    you will probably want to have the following in your code:
    if (records < 2)
      records = 2;
    The reason is that the server will optimize for cases of only a single
    record. If in a table scan you don't know the number of records
    it will probably be better to set records to two so you can return
    as many records as you need.

    Along with records a few more variables you may wish to set are:
      records
      deleted
      data_file_length
      index_file_length
      delete_length
      check_time
    Take a look at the public variables in handler.h for more information.

    Called in:
      filesort.cc
      ha_heap.cc
      item_sum.cc
      opt_sum.cc
      sql_delete.cc
     sql_delete.cc
     sql_derived.cc
      sql_select.cc
      sql_select.cc
      sql_select.cc
      sql_select.cc
      sql_select.cc
      sql_show.cc
      sql_show.cc
      sql_show.cc
      sql_show.cc
      sql_table.cc
      sql_union.cc
      sql_update.cc

    Some flags that are not implemented
      HA_STATUS_POS:
        This parameter is never used from the MySQL Server. It is checked in a
        place in MyISAM so could potentially be used by MyISAM specific
        programs.
      HA_STATUS_NO_LOCK:
      This is declared and often used. It's only used by MyISAM.
      It means that MySQL doesn't need the absolute latest statistics
      information. This may save the handler from doing internal locks while
      retrieving statistics data.
*/

int ha_partition::info(uint flag)
{
  uint no_lock_flag= flag & HA_STATUS_NO_LOCK;
  uint extra_var_flag= flag & HA_STATUS_VARIABLE_EXTRA;
  DBUG_ENTER("ha_partition::info");

#ifndef DBUG_OFF
  if (bitmap_is_set_all(&(m_part_info->read_partitions)))
    DBUG_PRINT("info", ("All partitions are used"));
#endif /* DBUG_OFF */
  if (flag & HA_STATUS_AUTO)
  {
    bool auto_inc_is_first_in_idx= (table_share->next_number_keypart == 0);
    DBUG_PRINT("info", ("HA_STATUS_AUTO"));
    if (!table->found_next_number_field)
      stats.auto_increment_value= 0;
    else if (part_share->auto_inc_initialized)
    {
      lock_auto_increment();
      stats.auto_increment_value= part_share->next_auto_inc_val;
      unlock_auto_increment();
    }
    else
    {
      lock_auto_increment();
      /* to avoid two concurrent initializations, check again when locked */
      if (part_share->auto_inc_initialized)
        stats.auto_increment_value= part_share->next_auto_inc_val;
      else
      {
        /*
          The auto-inc mutex in the table_share is locked, so we do not need
          to have the handlers locked.
          HA_STATUS_NO_LOCK is not checked, since we cannot skip locking
          the mutex, because it is initialized.
        */
        handler *file, **file_array;
        ulonglong auto_increment_value= 0;
        file_array= m_file;
        DBUG_PRINT("info",
                   ("checking all partitions for auto_increment_value"));
        do
        {
          file= *file_array;
          file->info(HA_STATUS_AUTO | no_lock_flag);
          set_if_bigger(auto_increment_value,
                        file->stats.auto_increment_value);
        } while (*(++file_array));

        DBUG_ASSERT(auto_increment_value);
        stats.auto_increment_value= auto_increment_value;
        if (auto_inc_is_first_in_idx)
        {
          set_if_bigger(part_share->next_auto_inc_val,
                        auto_increment_value);
          part_share->auto_inc_initialized= true;
          DBUG_PRINT("info", ("initializing next_auto_inc_val to %lu",
                       (ulong) part_share->next_auto_inc_val));
        }
      }
      unlock_auto_increment();
    }
  }
  if (flag & HA_STATUS_VARIABLE)
  {
    uint i;
    DBUG_PRINT("info", ("HA_STATUS_VARIABLE"));
    /*
      Calculates statistical variables
      records:           Estimate of number records in table
      We report sum (always at least 2 if not empty)
      deleted:           Estimate of number holes in the table due to
      deletes
      We report sum
      data_file_length:  Length of data file, in principle bytes in table
      We report sum
      index_file_length: Length of index file, in principle bytes in
      indexes in the table
      We report sum
      delete_length: Length of free space easily used by new records in table
      We report sum
      mean_record_length:Mean record length in the table
      We calculate this
      check_time:        Time of last check (only applicable to MyISAM)
      We report last time of all underlying handlers
    */
    handler *file;
    stats.records= 0;
    stats.deleted= 0;
    stats.data_file_length= 0;
    stats.index_file_length= 0;
    stats.check_time= 0;
    stats.delete_length= 0;
    for (i= bitmap_get_first_set(&m_part_info->read_partitions);
         i < m_tot_parts;
         i= bitmap_get_next_set(&m_part_info->read_partitions, i))
    {
      file= m_file[i];
      file->info(HA_STATUS_VARIABLE | no_lock_flag | extra_var_flag);
      stats.records+= file->stats.records;
      stats.deleted+= file->stats.deleted;
      stats.data_file_length+= file->stats.data_file_length;
      stats.index_file_length+= file->stats.index_file_length;
      stats.delete_length+= file->stats.delete_length;
      if (file->stats.check_time > stats.check_time)
        stats.check_time= file->stats.check_time;
    }
    if (stats.records && stats.records < 2 &&
        !(m_file[0]->ha_table_flags() & HA_STATS_RECORDS_IS_EXACT))
      stats.records= 2;
    if (stats.records > 0)
      stats.mean_rec_length= (ulong) (stats.data_file_length / stats.records);
    else
      stats.mean_rec_length= 0;
  }
  if (flag & HA_STATUS_CONST)
  {
    DBUG_PRINT("info", ("HA_STATUS_CONST"));
    /*
      Recalculate loads of constant variables. MyISAM also sets things
      directly on the table share object.

      Check whether this should be fixed since handlers should not
      change things directly on the table object.

      Monty comment: This should NOT be changed!  It's the handlers
      responsibility to correct table->s->keys_xxxx information if keys
      have been disabled.

      The most important parameters set here is records per key on
      all indexes. block_size and primar key ref_length.

      For each index there is an array of rec_per_key.
      As an example if we have an index with three attributes a,b and c
      we will have an array of 3 rec_per_key.
      rec_per_key[0] is an estimate of number of records divided by
      number of unique values of the field a.
      rec_per_key[1] is an estimate of the number of records divided
      by the number of unique combinations of the fields a and b.
      rec_per_key[2] is an estimate of the number of records divided
      by the number of unique combinations of the fields a,b and c.

      Many handlers only set the value of rec_per_key when all fields
      are bound (rec_per_key[2] in the example above).

      If the handler doesn't support statistics, it should set all of the
      above to 0.

      We first scans through all partitions to get the one holding most rows.
      We will then allow the handler with the most rows to set
      the rec_per_key and use this as an estimate on the total table.

      max_data_file_length:     Maximum data file length
      We ignore it, is only used in
      SHOW TABLE STATUS
      max_index_file_length:    Maximum index file length
      We ignore it since it is never used
      block_size:               Block size used
      We set it to the value of the first handler
      ref_length:               We set this to the value calculated
      and stored in local object
      create_time:              Creation time of table

      So we calculate these constants by using the variables from the
      handler with most rows.
    */
    handler *file, **file_array;
    ulonglong max_records= 0;
    uint32 i= 0;
    uint32 handler_instance= 0;

    file_array= m_file;
    do
    {
      file= *file_array;
      /* Get variables if not already done */
      if (!(flag & HA_STATUS_VARIABLE) ||
          !bitmap_is_set(&(m_part_info->read_partitions),
                         (file_array - m_file)))
        file->info(HA_STATUS_VARIABLE | no_lock_flag | extra_var_flag);
      if (file->stats.records > max_records)
      {
        max_records= file->stats.records;
        handler_instance= i;
      }
      i++;
    } while (*(++file_array));
    /*
      Sort the array of part_ids by number of records in
      in descending order.
    */
    my_qsort2((void*) m_part_ids_sorted_by_num_of_records,
              m_tot_parts,
              sizeof(uint32),
              (qsort2_cmp) compare_number_of_records,
              this);

    file= m_file[handler_instance];
    file->info(HA_STATUS_CONST | no_lock_flag);
    stats.block_size= file->stats.block_size;
    stats.create_time= file->stats.create_time;
    ref_length= m_ref_length;
  }
  if (flag & HA_STATUS_ERRKEY)
  {
    handler *file= m_file[m_last_part];
    DBUG_PRINT("info", ("info: HA_STATUS_ERRKEY"));
    /*
      This flag is used to get index number of the unique index that
      reported duplicate key
      We will report the errkey on the last handler used and ignore the rest
      Note: all engines does not support HA_STATUS_ERRKEY, so set errkey.
    */
    file->errkey= errkey;
    file->info(HA_STATUS_ERRKEY | no_lock_flag);
    errkey= file->errkey;
  }
  if (flag & HA_STATUS_TIME)
  {
    handler *file, **file_array;
    DBUG_PRINT("info", ("info: HA_STATUS_TIME"));
    /*
      This flag is used to set the latest update time of the table.
      Used by SHOW commands
      We will report the maximum of these times
    */
    stats.update_time= 0;
    file_array= m_file;
    do
    {
      file= *file_array;
      file->info(HA_STATUS_TIME | no_lock_flag);
      if (file->stats.update_time > stats.update_time)
        stats.update_time= file->stats.update_time;
    } while (*(++file_array));
  }
  DBUG_RETURN(0);
}


void ha_partition::get_dynamic_partition_info(PARTITION_STATS *stat_info,
                                              uint part_id)
{
  handler *file= m_file[part_id];
  DBUG_ASSERT(bitmap_is_set(&(m_part_info->read_partitions), part_id));
  file->info(HA_STATUS_TIME | HA_STATUS_VARIABLE |
             HA_STATUS_VARIABLE_EXTRA | HA_STATUS_NO_LOCK);

  stat_info->records=              file->stats.records;
  stat_info->mean_rec_length=      file->stats.mean_rec_length;
  stat_info->data_file_length=     file->stats.data_file_length;
  stat_info->max_data_file_length= file->stats.max_data_file_length;
  stat_info->index_file_length=    file->stats.index_file_length;
  stat_info->delete_length=        file->stats.delete_length;
  stat_info->create_time=          file->stats.create_time;
  stat_info->update_time=          file->stats.update_time;
  stat_info->check_time=           file->stats.check_time;
  stat_info->check_sum= 0;
  if (file->ha_table_flags() & HA_HAS_CHECKSUM)
    stat_info->check_sum= file->checksum();
  return;
}


int ha_partition::extra(enum ha_extra_function operation)
{
  DBUG_ENTER("ha_partition:extra");
  DBUG_PRINT("info", ("operation: %d", (int) operation));

  switch (operation) {
    /* Category 1), used by most handlers */
  case HA_EXTRA_KEYREAD:
  case HA_EXTRA_NO_KEYREAD:
  case HA_EXTRA_FLUSH:
    DBUG_RETURN(loop_extra(operation));
  case HA_EXTRA_PREPARE_FOR_RENAME:
  case HA_EXTRA_FORCE_REOPEN:
    DBUG_RETURN(loop_extra_alter(operation));
    break;

    /* Category 2), used by non-MyISAM handlers */
  case HA_EXTRA_IGNORE_DUP_KEY:
  case HA_EXTRA_NO_IGNORE_DUP_KEY:
  case HA_EXTRA_KEYREAD_PRESERVE_FIELDS:
  {
    if (!m_myisam)
      DBUG_RETURN(loop_extra(operation));
    break;
  }

  /* Category 3), used by MyISAM handlers */
  case HA_EXTRA_PREPARE_FOR_UPDATE:
    /*
      Needs to be run on the first partition in the range now, and 
      later in late_extra_cache, when switching to a new partition to scan.
    */
    m_extra_prepare_for_update= TRUE;
    if (m_part_spec.start_part != NO_CURRENT_PART_ID)
    {
      if (!m_extra_cache)
        m_extra_cache_part_id= m_part_spec.start_part;
      DBUG_ASSERT(m_extra_cache_part_id == m_part_spec.start_part);
      (void) m_file[m_part_spec.start_part]->extra(HA_EXTRA_PREPARE_FOR_UPDATE);
    }
    break;
  case HA_EXTRA_NORMAL:
  case HA_EXTRA_QUICK:
  case HA_EXTRA_PREPARE_FOR_DROP:
  case HA_EXTRA_FLUSH_CACHE:
  {
    if (m_myisam)
      DBUG_RETURN(loop_extra(operation));
    break;
  }
  case HA_EXTRA_NO_READCHECK:
  {
    /*
      This is only done as a part of ha_open, which is also used in
      ha_partition::open, so no need to do anything.
    */
    break;
  }
  case HA_EXTRA_CACHE:
  {
    prepare_extra_cache(0);
    break;
  }
  case HA_EXTRA_NO_CACHE:
  {
    int ret= 0;
    if (m_extra_cache_part_id != NO_CURRENT_PART_ID)
      ret= m_file[m_extra_cache_part_id]->extra(HA_EXTRA_NO_CACHE);
    m_extra_cache= FALSE;
    m_extra_cache_size= 0;
    m_extra_prepare_for_update= FALSE;
    m_extra_cache_part_id= NO_CURRENT_PART_ID;
    DBUG_RETURN(ret);
  }
  case HA_EXTRA_WRITE_CACHE:
  {
    m_extra_cache= FALSE;
    m_extra_cache_size= 0;
    m_extra_prepare_for_update= FALSE;
    m_extra_cache_part_id= NO_CURRENT_PART_ID;
    DBUG_RETURN(loop_extra(operation));
  }
  case HA_EXTRA_IGNORE_NO_KEY:
  case HA_EXTRA_NO_IGNORE_NO_KEY:
  {
    /*
      Ignore as these are specific to NDB for handling
      idempotency
     */
    break;
  }
  case HA_EXTRA_WRITE_CAN_REPLACE:
  case HA_EXTRA_WRITE_CANNOT_REPLACE:
  {
    /*
      Informs handler that write_row() can replace rows which conflict
      with row being inserted by PK/unique key without reporting error
      to the SQL-layer.

      This optimization is not safe for partitioned table in general case
      since we may have to put new version of row into partition which is
      different from partition in which old version resides (for example
      when we partition by non-PK column or by some column which is not
      part of unique key which were violated).
      And since NDB which is the only engine at the moment that supports
      this optimization handles partitioning on its own we simple disable
      it here. (BTW for NDB this optimization is safe since it supports
      only KEY partitioning and won't use this optimization for tables
      which have additional unique constraints).
    */
    break;
  }
    /* Category 7), used by federated handlers */
  case HA_EXTRA_INSERT_WITH_UPDATE:
    DBUG_RETURN(loop_extra(operation));
    /* Category 8) Operations only used by NDB */
  case HA_EXTRA_DELETE_CANNOT_BATCH:
  case HA_EXTRA_UPDATE_CANNOT_BATCH:
  {
    /* Currently only NDB use the *_CANNOT_BATCH */
    break;
  }
    /* Category 9) Operations only used by MERGE */
  case HA_EXTRA_ADD_CHILDREN_LIST:
  case HA_EXTRA_ATTACH_CHILDREN:
  case HA_EXTRA_IS_ATTACHED_CHILDREN:
  case HA_EXTRA_DETACH_CHILDREN:
  {
    /* Special actions for MERGE tables. Ignore. */
    break;
  }
  /*
    http://dev.mysql.com/doc/refman/5.1/en/partitioning-limitations.html
    says we no longer support logging to partitioned tables, so we fail
    here.
  */
  case HA_EXTRA_MARK_AS_LOG_TABLE:
    DBUG_RETURN(ER_UNSUPORTED_LOG_ENGINE);
  default:
  {
    /* Temporary crash to discover what is wrong */
    DBUG_ASSERT(0);
    break;
  }
  }
  DBUG_RETURN(0);
}


int ha_partition::reset(void)
{
  int result= 0;
  int tmp;
  uint i;
  DBUG_ENTER("ha_partition::reset");

  for (i= bitmap_get_first_set(&m_partitions_to_reset);
       i < m_tot_parts;
       i= bitmap_get_next_set(&m_partitions_to_reset, i))
  {
    if ((tmp= m_file[i]->ha_reset()))
      result= tmp;
  }
  bitmap_clear_all(&m_partitions_to_reset);
  DBUG_RETURN(result);
}

/*
  Special extra method for HA_EXTRA_CACHE with cachesize as extra parameter

  SYNOPSIS
    extra_opt()
    operation                      Must be HA_EXTRA_CACHE
    cachesize                      Size of cache in full table scan

  RETURN VALUE
    >0                   Error code
    0                    Success
*/

int ha_partition::extra_opt(enum ha_extra_function operation, ulong cachesize)
{
  DBUG_ENTER("ha_partition::extra_opt()");

  DBUG_ASSERT(HA_EXTRA_CACHE == operation);
  prepare_extra_cache(cachesize);
  DBUG_RETURN(0);
}


/*
  Call extra on handler with HA_EXTRA_CACHE and cachesize

  SYNOPSIS
    prepare_extra_cache()
    cachesize                Size of cache for full table scan

  RETURN VALUE
    NONE
*/

void ha_partition::prepare_extra_cache(uint cachesize)
{
  DBUG_ENTER("ha_partition::prepare_extra_cache()");
  DBUG_PRINT("info", ("cachesize %u", cachesize));

  m_extra_cache= TRUE;
  m_extra_cache_size= cachesize;
  if (m_part_spec.start_part != NO_CURRENT_PART_ID)
  {
    DBUG_ASSERT(bitmap_is_set(&m_partitions_to_reset,
                              m_part_spec.start_part));
    bitmap_set_bit(&m_partitions_to_reset, m_part_spec.start_part);
    late_extra_cache(m_part_spec.start_part);
  }
  DBUG_VOID_RETURN;
}


int ha_partition::loop_extra_alter(enum ha_extra_function operation)
{
  int result= 0, tmp;
  handler **file;
  DBUG_ENTER("ha_partition::loop_extra_alter()");
  DBUG_ASSERT(operation == HA_EXTRA_PREPARE_FOR_RENAME ||
              operation == HA_EXTRA_FORCE_REOPEN);

  if (m_new_file != NULL)
  {
    for (file= m_new_file; *file; file++)
      if ((tmp= (*file)->extra(operation)))
        result= tmp;
  }
  if (m_reorged_file != NULL)
  {
    for (file= m_reorged_file; *file; file++)
      if ((tmp= (*file)->extra(operation)))
        result= tmp;
  }
  if ((tmp= loop_extra(operation)))
    result= tmp;
  DBUG_RETURN(result);
}

/*
  Call extra on all partitions

  SYNOPSIS
    loop_extra()
    operation             extra operation type

  RETURN VALUE
    >0                    Error code
    0                     Success
*/

int ha_partition::loop_extra(enum ha_extra_function operation)
{
  int result= 0, tmp;
  uint i;
  DBUG_ENTER("ha_partition::loop_extra()");
  
  for (i= bitmap_get_first_set(&m_part_info->lock_partitions);
       i < m_tot_parts;
       i= bitmap_get_next_set(&m_part_info->lock_partitions, i))
  {
    if ((tmp= m_file[i]->extra(operation)))
      result= tmp;
  }
  /* Add all used partitions to be called in reset(). */
  bitmap_union(&m_partitions_to_reset, &m_part_info->lock_partitions);
  DBUG_RETURN(result);
}


/*
  Call extra(HA_EXTRA_CACHE) on next partition_id

  SYNOPSIS
    late_extra_cache()
    partition_id               Partition id to call extra on

  RETURN VALUE
    NONE
*/

void ha_partition::late_extra_cache(uint partition_id)
{
  handler *file;
  DBUG_ENTER("ha_partition::late_extra_cache");
  DBUG_PRINT("info", ("extra_cache %u prepare %u partid %u size %u",
                      m_extra_cache, m_extra_prepare_for_update,
                      partition_id, m_extra_cache_size));

  if (!m_extra_cache && !m_extra_prepare_for_update)
    DBUG_VOID_RETURN;
  file= m_file[partition_id];
  if (m_extra_cache)
  {
    if (m_extra_cache_size == 0)
      (void) file->extra(HA_EXTRA_CACHE);
    else
      (void) file->extra_opt(HA_EXTRA_CACHE, m_extra_cache_size);
  }
  if (m_extra_prepare_for_update)
  {
    (void) file->extra(HA_EXTRA_PREPARE_FOR_UPDATE);
  }
  m_extra_cache_part_id= partition_id;
  DBUG_VOID_RETURN;
}


/*
  Call extra(HA_EXTRA_NO_CACHE) on next partition_id

  SYNOPSIS
    late_extra_no_cache()
    partition_id               Partition id to call extra on

  RETURN VALUE
    NONE
*/

void ha_partition::late_extra_no_cache(uint partition_id)
{
  handler *file;
  DBUG_ENTER("ha_partition::late_extra_no_cache");

  if (!m_extra_cache && !m_extra_prepare_for_update)
    DBUG_VOID_RETURN;
  file= m_file[partition_id];
  (void) file->extra(HA_EXTRA_NO_CACHE);
  DBUG_ASSERT(partition_id == m_extra_cache_part_id);
  m_extra_cache_part_id= NO_CURRENT_PART_ID;
  DBUG_VOID_RETURN;
}


/****************************************************************************
                MODULE optimiser support
****************************************************************************/

const key_map *ha_partition::keys_to_use_for_scanning()
{
  DBUG_ENTER("ha_partition::keys_to_use_for_scanning");
  DBUG_RETURN(m_file[0]->keys_to_use_for_scanning());
}


ha_rows ha_partition::min_rows_for_estimate()
{
  uint i, max_used_partitions, tot_used_partitions;
  DBUG_ENTER("ha_partition::min_rows_for_estimate");

  tot_used_partitions= bitmap_bits_set(&m_part_info->read_partitions);

  /*
    All partitions might have been left as unused during partition pruning
    due to, for example, an impossible WHERE condition. Nonetheless, the
    optimizer might still attempt to perform (e.g. range) analysis where an
    estimate of the the number of rows is calculated using records_in_range.
    Hence, to handle this and other possible cases, use zero as the minimum
    number of rows to base the estimate on if no partition is being used.
  */
  if (!tot_used_partitions)
    DBUG_RETURN(0);

  /*
    Allow O(log2(tot_partitions)) increase in number of used partitions.
    This gives O(tot_rows/log2(tot_partitions)) rows to base the estimate on.
    I.e when the total number of partitions doubles, allow one more
    partition to be checked.
  */
  i= 2;
  max_used_partitions= 1;
  while (i < m_tot_parts)
  {
    max_used_partitions++;
    i= i << 1;
  }
  if (max_used_partitions > tot_used_partitions)
    max_used_partitions= tot_used_partitions;

  /* stats.records is already updated by the info(HA_STATUS_VARIABLE) call. */
  DBUG_PRINT("info", ("max_used_partitions: %u tot_rows: %lu",
                      max_used_partitions,
                      (ulong) stats.records));
  DBUG_PRINT("info", ("tot_used_partitions: %u min_rows_to_check: %lu",
                      tot_used_partitions,
                      (ulong) stats.records * max_used_partitions
                              / tot_used_partitions));
  DBUG_RETURN(stats.records * max_used_partitions / tot_used_partitions);
}


uint ha_partition::get_biggest_used_partition(uint *part_index)
{
  uint part_id;
  while ((*part_index) < m_tot_parts)
  {
    part_id= m_part_ids_sorted_by_num_of_records[(*part_index)++];
    if (bitmap_is_set(&m_part_info->read_partitions, part_id))
      return part_id;
  }
  return NO_CURRENT_PART_ID;
}


/*
  Return time for a scan of the table

  SYNOPSIS
    scan_time()

  RETURN VALUE
    time for scan
*/

double ha_partition::scan_time()
{
  double scan_time= 0;
  uint i;
  DBUG_ENTER("ha_partition::scan_time");

  for (i= bitmap_get_first_set(&m_part_info->read_partitions);
       i < m_tot_parts;
       i= bitmap_get_next_set(&m_part_info->read_partitions, i))
    scan_time+= m_file[i]->scan_time();
  DBUG_RETURN(scan_time);
}


ha_rows ha_partition::records_in_range(uint inx, key_range *min_key,
                                       key_range *max_key)
{
  ha_rows min_rows_to_check, rows, estimated_rows=0, checked_rows= 0;
  uint partition_index= 0, part_id;
  DBUG_ENTER("ha_partition::records_in_range");

  min_rows_to_check= min_rows_for_estimate();

  while ((part_id= get_biggest_used_partition(&partition_index))
         != NO_CURRENT_PART_ID)
  {
    rows= m_file[part_id]->records_in_range(inx, min_key, max_key);
      
    DBUG_PRINT("info", ("part %u match %lu rows of %lu", part_id, (ulong) rows,
                        (ulong) m_file[part_id]->stats.records));

    if (rows == HA_POS_ERROR)
      DBUG_RETURN(HA_POS_ERROR);
    estimated_rows+= rows;
    checked_rows+= m_file[part_id]->stats.records;
    /*
      Returning 0 means no rows can be found, so we must continue
      this loop as long as we have estimated_rows == 0.
      Also many engines return 1 to indicate that there may exist
      a matching row, we do not normalize this by dividing by number of
      used partitions, but leave it to be returned as a sum, which will
      reflect that we will need to scan each partition's index.

      Note that this statistics may not always be correct, so we must
      continue even if the current partition has 0 rows, since we might have
      deleted rows from the current partition, or inserted to the next
      partition.
    */
    if (estimated_rows && checked_rows &&
        checked_rows >= min_rows_to_check)
    {
      DBUG_PRINT("info",
                 ("records_in_range(inx %u): %lu (%lu * %lu / %lu)",
                  inx,
                  (ulong) (estimated_rows * stats.records / checked_rows),
                  (ulong) estimated_rows,
                  (ulong) stats.records,
                  (ulong) checked_rows));
      DBUG_RETURN(estimated_rows * stats.records / checked_rows);
    }
  }
  DBUG_PRINT("info", ("records_in_range(inx %u): %lu",
                      inx,
                      (ulong) estimated_rows));
  DBUG_RETURN(estimated_rows);
}


ha_rows ha_partition::estimate_rows_upper_bound()
{
  ha_rows rows, tot_rows= 0;
  handler **file= m_file;
  DBUG_ENTER("ha_partition::estimate_rows_upper_bound");

  do
  {
    if (bitmap_is_set(&(m_part_info->read_partitions), (file - m_file)))
    {
      rows= (*file)->estimate_rows_upper_bound();
      if (rows == HA_POS_ERROR)
        DBUG_RETURN(HA_POS_ERROR);
      tot_rows+= rows;
    }
  } while (*(++file));
  DBUG_RETURN(tot_rows);
}


/*
  Get time to read

  SYNOPSIS
    read_time()
    index                Index number used
    ranges               Number of ranges
    rows                 Number of rows

  RETURN VALUE
    time for read

  DESCRIPTION
    This will be optimised later to include whether or not the index can
    be used with partitioning. To achieve we need to add another parameter
    that specifies how many of the index fields that are bound in the ranges.
    Possibly added as a new call to handlers.
*/

double ha_partition::read_time(uint index, uint ranges, ha_rows rows)
{
  DBUG_ENTER("ha_partition::read_time");

  DBUG_RETURN(m_file[0]->read_time(index, ranges, rows));
}


ha_rows ha_partition::records()
{
  ha_rows rows, tot_rows= 0;
  uint i;
  DBUG_ENTER("ha_partition::records");

  for (i= bitmap_get_first_set(&m_part_info->read_partitions);
       i < m_tot_parts;
       i= bitmap_get_next_set(&m_part_info->read_partitions, i))
  {
    rows= m_file[i]->records();
    if (rows == HA_POS_ERROR)
      DBUG_RETURN(HA_POS_ERROR);
    tot_rows+= rows;
  }
  DBUG_RETURN(tot_rows);
}


/*
  Is it ok to switch to a new engine for this table

  SYNOPSIS
    can_switch_engine()

  RETURN VALUE
    TRUE                  Ok
    FALSE                 Not ok

  DESCRIPTION
    Used to ensure that tables with foreign key constraints are not moved
    to engines without foreign key support.
*/

bool ha_partition::can_switch_engines()
{
  handler **file;
  DBUG_ENTER("ha_partition::can_switch_engines");
 
  file= m_file;
  do
  {
    if (!(*file)->can_switch_engines())
      DBUG_RETURN(FALSE);
  } while (*(++file));
  DBUG_RETURN(TRUE);
}


/*
  Is table cache supported

  SYNOPSIS
    table_cache_type()

*/

uint8 ha_partition::table_cache_type()
{
  DBUG_ENTER("ha_partition::table_cache_type");

  DBUG_RETURN(m_file[0]->table_cache_type());
}


uint32 ha_partition::calculate_key_hash_value(Field **field_array)
{
  ulong nr1= 1;
  ulong nr2= 4;
  bool use_51_hash;
  use_51_hash= test((*field_array)->table->part_info->key_algorithm ==
                    partition_info::KEY_ALGORITHM_51);

  do
  {
    Field *field= *field_array;
    if (use_51_hash)
    {
      switch (field->real_type()) {
      case MYSQL_TYPE_TINY:
      case MYSQL_TYPE_SHORT:
      case MYSQL_TYPE_LONG:
      case MYSQL_TYPE_FLOAT:
      case MYSQL_TYPE_DOUBLE:
      case MYSQL_TYPE_NEWDECIMAL:
      case MYSQL_TYPE_TIMESTAMP:
      case MYSQL_TYPE_LONGLONG:
      case MYSQL_TYPE_INT24:
      case MYSQL_TYPE_TIME:
      case MYSQL_TYPE_DATETIME:
      case MYSQL_TYPE_YEAR:
      case MYSQL_TYPE_NEWDATE:
        {
          if (field->is_null())
          {
            nr1^= (nr1 << 1) | 1;
            continue;
          }
          /* Force this to my_hash_sort_bin, which was used in 5.1! */
          uint len= field->pack_length();
          my_charset_bin.coll->hash_sort(&my_charset_bin, field->ptr, len,
                                         &nr1, &nr2);
          /* Done with this field, continue with next one. */
          continue;
        }
      case MYSQL_TYPE_STRING:
      case MYSQL_TYPE_VARCHAR:
      case MYSQL_TYPE_BIT:
        /* Not affected, same in 5.1 and 5.5 */
        break;
      /*
        ENUM/SET uses my_hash_sort_simple in 5.1 (i.e. my_charset_latin1)
        and my_hash_sort_bin in 5.5!
      */
      case MYSQL_TYPE_ENUM:
      case MYSQL_TYPE_SET:
        {
          if (field->is_null())
          {
            nr1^= (nr1 << 1) | 1;
            continue;
          }
          /* Force this to my_hash_sort_bin, which was used in 5.1! */
          uint len= field->pack_length();
          my_charset_latin1.coll->hash_sort(&my_charset_latin1, field->ptr,
                                            len, &nr1, &nr2);
          continue;
        }
      /* New types in mysql-5.6. */
      case MYSQL_TYPE_DATETIME2:
      case MYSQL_TYPE_TIME2:
      case MYSQL_TYPE_TIMESTAMP2:
        /* Not affected, 5.6+ only! */
        break;

      /* These types should not be allowed for partitioning! */
      case MYSQL_TYPE_NULL:
      case MYSQL_TYPE_DECIMAL:
      case MYSQL_TYPE_DATE:
      case MYSQL_TYPE_TINY_BLOB:
      case MYSQL_TYPE_MEDIUM_BLOB:
      case MYSQL_TYPE_LONG_BLOB:
      case MYSQL_TYPE_BLOB:
      case MYSQL_TYPE_VAR_STRING:
      case MYSQL_TYPE_GEOMETRY:
        /* fall through. */
      default:
        DBUG_ASSERT(0);                    // New type?
        /* Fall through for default hashing (5.5). */
      }
      /* fall through, use collation based hashing. */
    }
    field->hash(&nr1, &nr2);
  } while (*(++field_array));
  return (uint32) nr1;
}


/****************************************************************************
                MODULE print messages
****************************************************************************/

const char *ha_partition::index_type(uint inx)
{
  uint first_used_partition;
  DBUG_ENTER("ha_partition::index_type");

  first_used_partition= bitmap_get_first_set(&(m_part_info->read_partitions));

  if (first_used_partition == MY_BIT_NONE)
  {
    DBUG_ASSERT(0);                             // How can this happen?
    DBUG_RETURN(handler::index_type(inx));
  }

  DBUG_RETURN(m_file[first_used_partition]->index_type(inx));
}


enum row_type ha_partition::get_row_type() const
{
  uint i;
  enum row_type type;
  DBUG_ENTER("ha_partition::get_row_type");

  i= bitmap_get_first_set(&m_part_info->read_partitions);
  DBUG_ASSERT(i < m_tot_parts);
  if (i >= m_tot_parts)
    DBUG_RETURN(ROW_TYPE_NOT_USED);

  type= m_file[i]->get_row_type();
  DBUG_PRINT("info", ("partition %u, row_type: %d", i, type));

  for (i= bitmap_get_next_set(&m_part_info->lock_partitions, i);
       i < m_tot_parts;
       i= bitmap_get_next_set(&m_part_info->lock_partitions, i))
  {
    enum row_type part_type= m_file[i]->get_row_type();
    DBUG_PRINT("info", ("partition %u, row_type: %d", i, type));
    if (part_type != type)
      DBUG_RETURN(ROW_TYPE_NOT_USED);
  }

  DBUG_RETURN(type);
}


void ha_partition::append_row_to_str(String &str)
{
  const uchar *rec;
  bool is_rec0= !m_err_rec || m_err_rec == table->record[0];
  if (is_rec0)
    rec= table->record[0];
  else
    rec= m_err_rec;
  // If PK, use full PK instead of full part field array!
  if (table->s->primary_key != MAX_KEY)
  {
    KEY *key= table->key_info + table->s->primary_key;
    KEY_PART_INFO *key_part=     key->key_part;
    KEY_PART_INFO *key_part_end= key_part + key->user_defined_key_parts;
    if (!is_rec0)
      set_key_field_ptr(key, rec, table->record[0]);
    for (; key_part != key_part_end; key_part++)
    {
      Field *field= key_part->field;
      str.append(" ");
      str.append(field->field_name);
      str.append(":");
      field_unpack(&str, field, rec, 0, false);
    }
    if (!is_rec0)
      set_key_field_ptr(key, table->record[0], rec);
  }
  else
  {
    Field **field_ptr;
    if (!is_rec0)
      set_field_ptr(m_part_info->full_part_field_array, rec,
                    table->record[0]);
    /* No primary key, use full partition field array. */
    for (field_ptr= m_part_info->full_part_field_array;
         *field_ptr;
         field_ptr++)
    {
      Field *field= *field_ptr;
      str.append(" ");
      str.append(field->field_name);
      str.append(":");
      field_unpack(&str, field, rec, 0, false);
    }
    if (!is_rec0)
      set_field_ptr(m_part_info->full_part_field_array, table->record[0],
                    rec);
  }
}


void ha_partition::print_error(int error, myf errflag)
{
  THD *thd= ha_thd();
  DBUG_ENTER("ha_partition::print_error");

  /* Should probably look for my own errors first */
  DBUG_PRINT("enter", ("error: %d", error));

  if ((error == HA_ERR_NO_PARTITION_FOUND) &&
      ! (thd->lex->alter_info.flags & Alter_info::ALTER_TRUNCATE_PARTITION))
    m_part_info->print_no_partition_found(table);
  else if (error == HA_ERR_ROW_IN_WRONG_PARTITION)
  {
    /* Should only happen on DELETE or UPDATE! */
    DBUG_ASSERT(thd_sql_command(thd) == SQLCOM_DELETE ||
                thd_sql_command(thd) == SQLCOM_DELETE_MULTI ||
                thd_sql_command(thd) == SQLCOM_UPDATE ||
                thd_sql_command(thd) == SQLCOM_UPDATE_MULTI);
    DBUG_ASSERT(m_err_rec);
    if (m_err_rec)
    {
      uint max_length;
      char buf[MAX_KEY_LENGTH];
      String str(buf,sizeof(buf),system_charset_info);
      uint32 part_id;
      str.length(0);
      str.append("(");
      str.append_ulonglong(m_last_part);
      str.append(" != ");
      if (get_part_for_delete(m_err_rec, m_rec0, m_part_info, &part_id))
        str.append("?");
      else
        str.append_ulonglong(part_id);
      str.append(")");
      append_row_to_str(str);

      /* Log this error, so the DBA can notice it and fix it! */
      sql_print_error("Table '%-192s' corrupted: row in wrong partition: %s\n"
                      "Please REPAIR the table!",
                      table->s->table_name.str,
                      str.c_ptr_safe());

      max_length= (MYSQL_ERRMSG_SIZE - (uint) strlen(ER(ER_ROW_IN_WRONG_PARTITION)));
      if (str.length() >= max_length)
      {
        str.length(max_length-4);
        str.append(STRING_WITH_LEN("..."));
      }
      my_error(ER_ROW_IN_WRONG_PARTITION, MYF(0), str.c_ptr_safe());
      m_err_rec= NULL;
      DBUG_VOID_RETURN;
    }
    /* fall through to generic error handling. */
  }

  /* In case m_file has not been initialized, like in bug#42438 */
  if (m_file)
  {
    if (m_last_part >= m_tot_parts)
    {
      DBUG_ASSERT(0);
      m_last_part= 0;
    }
    m_file[m_last_part]->print_error(error, errflag);
  }
  else
    handler::print_error(error, errflag);
  DBUG_VOID_RETURN;
}


bool ha_partition::get_error_message(int error, String *buf)
{
  DBUG_ENTER("ha_partition::get_error_message");

  /* Should probably look for my own errors first */

  /* In case m_file has not been initialized, like in bug#42438 */
  if (m_file)
    DBUG_RETURN(m_file[m_last_part]->get_error_message(error, buf));
  DBUG_RETURN(handler::get_error_message(error, buf));

}


/****************************************************************************
                MODULE in-place ALTER
****************************************************************************/
handler::Table_flags ha_partition::table_flags() const
{
  uint first_used_partition= 0;
  DBUG_ENTER("ha_partition::table_flags");
  if (m_handler_status < handler_initialized ||
      m_handler_status >= handler_closed)
    DBUG_RETURN(PARTITION_ENABLED_TABLE_FLAGS);

  if (get_lock_type() != F_UNLCK)
  {
    /*
      The flags are cached after external_lock, and may depend on isolation
      level. So we should use a locked partition to get the correct flags.
    */
    first_used_partition= bitmap_get_first_set(&m_part_info->lock_partitions);
    if (first_used_partition == MY_BIT_NONE)
      first_used_partition= 0;
  }
  DBUG_RETURN((m_file[first_used_partition]->ha_table_flags() &
                 ~(PARTITION_DISABLED_TABLE_FLAGS)) |
                 (PARTITION_ENABLED_TABLE_FLAGS));
}


uint ha_partition::alter_table_flags(uint flags)
{
  uint flags_to_return;
  DBUG_ENTER("ha_partition::alter_table_flags");

  flags_to_return= ht->alter_table_flags(flags);
  flags_to_return|= m_file[0]->alter_table_flags(flags);

  DBUG_RETURN(flags_to_return);
}


bool ha_partition::check_if_incompatible_data(HA_CREATE_INFO *create_info,
                                              uint table_changes)
{
  handler **file;
  bool ret= COMPATIBLE_DATA_YES;

  /*
    The check for any partitioning related changes have already been done
    in mysql_alter_table (by fix_partition_func), so it is only up to
    the underlying handlers.
  */
  for (file= m_file; *file; file++)
    if ((ret=  (*file)->check_if_incompatible_data(create_info,
                                                   table_changes)) !=
        COMPATIBLE_DATA_YES)
      break;
  return ret;
}


class ha_partition_inplace_ctx : public inplace_alter_handler_ctx
{
public:
  inplace_alter_handler_ctx **handler_ctx_array;
private:
  uint m_tot_parts;

public:
  ha_partition_inplace_ctx(THD *thd, uint tot_parts)
    : inplace_alter_handler_ctx(),
      handler_ctx_array(NULL),
      m_tot_parts(tot_parts)
  {}

  ~ha_partition_inplace_ctx()
  {
    if (handler_ctx_array)
    {
      for (uint index= 0; index < m_tot_parts; index++)
        delete handler_ctx_array[index];
    }
  }
};


enum_alter_inplace_result
ha_partition::check_if_supported_inplace_alter(TABLE *altered_table,
                                               Alter_inplace_info *ha_alter_info)
{
  uint index= 0;
  enum_alter_inplace_result result= HA_ALTER_INPLACE_NO_LOCK;
  ha_partition_inplace_ctx *part_inplace_ctx;
  bool first_is_set= false;
  THD *thd= ha_thd();

  DBUG_ENTER("ha_partition::check_if_supported_inplace_alter");
  /*
    Support inplace change of KEY () -> KEY ALGORITHM = N ().
    Any other change would set partition_changed in
    prep_alter_part_table() in mysql_alter_table().
  */
  if (ha_alter_info->alter_info->flags == Alter_info::ALTER_PARTITION)
    DBUG_RETURN(HA_ALTER_INPLACE_NO_LOCK);

  part_inplace_ctx=
    new (thd->mem_root) ha_partition_inplace_ctx(thd, m_tot_parts);
  if (!part_inplace_ctx)
    DBUG_RETURN(HA_ALTER_ERROR);

  part_inplace_ctx->handler_ctx_array= (inplace_alter_handler_ctx **)
    thd->alloc(sizeof(inplace_alter_handler_ctx *) * (m_tot_parts + 1));
  if (!part_inplace_ctx->handler_ctx_array)
    DBUG_RETURN(HA_ALTER_ERROR);

  /* Set all to NULL, including the terminating one. */
  for (index= 0; index <= m_tot_parts; index++)
    part_inplace_ctx->handler_ctx_array[index]= NULL;

  for (index= 0; index < m_tot_parts; index++)
  {
    enum_alter_inplace_result p_result=
      m_file[index]->check_if_supported_inplace_alter(altered_table,
                                                      ha_alter_info);
    part_inplace_ctx->handler_ctx_array[index]= ha_alter_info->handler_ctx;

    if (index == 0)
    {
      first_is_set= (ha_alter_info->handler_ctx != NULL);
    }
    else if (first_is_set != (ha_alter_info->handler_ctx != NULL))
    {
      /* Either none or all partitions must set handler_ctx! */
      DBUG_ASSERT(0);
      DBUG_RETURN(HA_ALTER_ERROR);
    }
    if (p_result < result)
      result= p_result;
    if (result == HA_ALTER_ERROR)
      break;
  }

  ha_alter_info->handler_ctx= part_inplace_ctx;
  /*
    To indicate for future inplace calls that there are several
    partitions/handlers that need to be committed together,
    we set group_commit_ctx to the NULL terminated array of
    the partitions handlers.
  */
  ha_alter_info->group_commit_ctx= part_inplace_ctx->handler_ctx_array;

  DBUG_RETURN(result);
}


bool ha_partition::prepare_inplace_alter_table(TABLE *altered_table,
                                               Alter_inplace_info *ha_alter_info)
{
  uint index= 0;
  bool error= false;
  ha_partition_inplace_ctx *part_inplace_ctx;

  DBUG_ENTER("ha_partition::prepare_inplace_alter_table");

  /*
    Changing to similar partitioning, only update metadata.
    Non allowed changes would be catched in prep_alter_part_table().
  */
  if (ha_alter_info->alter_info->flags == Alter_info::ALTER_PARTITION)
    DBUG_RETURN(false);

  part_inplace_ctx=
    static_cast<class ha_partition_inplace_ctx*>(ha_alter_info->handler_ctx);

  for (index= 0; index < m_tot_parts && !error; index++)
  {
    ha_alter_info->handler_ctx= part_inplace_ctx->handler_ctx_array[index];
    if (m_file[index]->ha_prepare_inplace_alter_table(altered_table,
                                                      ha_alter_info))
      error= true;
    part_inplace_ctx->handler_ctx_array[index]= ha_alter_info->handler_ctx;
  }
  ha_alter_info->handler_ctx= part_inplace_ctx;

  DBUG_RETURN(error);
}


bool ha_partition::inplace_alter_table(TABLE *altered_table,
                                       Alter_inplace_info *ha_alter_info)
{
  uint index= 0;
  bool error= false;
  ha_partition_inplace_ctx *part_inplace_ctx;

  DBUG_ENTER("ha_partition::inplace_alter_table");

  /*
    Changing to similar partitioning, only update metadata.
    Non allowed changes would be catched in prep_alter_part_table().
  */
  if (ha_alter_info->alter_info->flags == Alter_info::ALTER_PARTITION)
    DBUG_RETURN(false);

  part_inplace_ctx=
    static_cast<class ha_partition_inplace_ctx*>(ha_alter_info->handler_ctx);

  for (index= 0; index < m_tot_parts && !error; index++)
  {
    ha_alter_info->handler_ctx= part_inplace_ctx->handler_ctx_array[index];
    if (m_file[index]->ha_inplace_alter_table(altered_table,
                                              ha_alter_info))
      error= true;
    part_inplace_ctx->handler_ctx_array[index]= ha_alter_info->handler_ctx;
  }
  ha_alter_info->handler_ctx= part_inplace_ctx;

  DBUG_RETURN(error);
}


/*
  Note that this function will try rollback failed ADD INDEX by
  executing DROP INDEX for the indexes that were committed (if any)
  before the error occured. This means that the underlying storage
  engine must be able to drop index in-place with X-lock held.
  (As X-lock will be held here if new indexes are to be committed)
*/
bool ha_partition::commit_inplace_alter_table(TABLE *altered_table,
                                              Alter_inplace_info *ha_alter_info,
                                              bool commit)
{
  ha_partition_inplace_ctx *part_inplace_ctx;
  bool error= false;

  DBUG_ENTER("ha_partition::commit_inplace_alter_table");

  /*
    Changing to similar partitioning, only update metadata.
    Non allowed changes would be catched in prep_alter_part_table().
  */
  if (ha_alter_info->alter_info->flags == Alter_info::ALTER_PARTITION)
    DBUG_RETURN(false);

  part_inplace_ctx=
    static_cast<class ha_partition_inplace_ctx*>(ha_alter_info->handler_ctx);

  if (commit)
  {
    DBUG_ASSERT(ha_alter_info->group_commit_ctx ==
                part_inplace_ctx->handler_ctx_array);
    ha_alter_info->handler_ctx= part_inplace_ctx->handler_ctx_array[0];
    error= m_file[0]->ha_commit_inplace_alter_table(altered_table,
                                                    ha_alter_info, commit);
    if (error)
      goto end;
    if (ha_alter_info->group_commit_ctx)
    {
      /*
        If ha_alter_info->group_commit_ctx is not set to NULL,
        then the engine did only commit the first partition!
        The engine is probably new, since both innodb and the default
        implementation of handler::commit_inplace_alter_table sets it to NULL
        and simply return false, since it allows metadata changes only.
        Loop over all other partitions as to follow the protocol!
      */
      uint i;
      DBUG_ASSERT(0);
      for (i= 1; i < m_tot_parts; i++)
      {
        ha_alter_info->handler_ctx= part_inplace_ctx->handler_ctx_array[i];
        error|= m_file[i]->ha_commit_inplace_alter_table(altered_table,
                                                         ha_alter_info,
                                                         true);
      }
    }
  }
  else
  {
    uint i;
    for (i= 0; i < m_tot_parts; i++)
    {
      /* Rollback, commit == false,  is done for each partition! */
      ha_alter_info->handler_ctx= part_inplace_ctx->handler_ctx_array[i];
      if (m_file[i]->ha_commit_inplace_alter_table(altered_table,
                                                   ha_alter_info, false))
        error= true;
    }
  }
end:
  ha_alter_info->handler_ctx= part_inplace_ctx;

  DBUG_RETURN(error);
}


void ha_partition::notify_table_changed()
{
  handler **file;

  DBUG_ENTER("ha_partition::notify_table_changed");

  for (file= m_file; *file; file++)
    (*file)->ha_notify_table_changed();

  DBUG_VOID_RETURN;
}


/*
  If frm_error() is called then we will use this to to find out what file
  extensions exist for the storage engine. This is also used by the default
  rename_table and delete_table method in handler.cc.
*/

static const char *ha_partition_ext[]=
{
  ha_par_ext, NullS
};

const char **ha_partition::bas_ext() const
{ return ha_partition_ext; }


uint ha_partition::min_of_the_max_uint(
                       uint (handler::*operator_func)(void) const) const
{
  handler **file;
  uint min_of_the_max= ((*m_file)->*operator_func)();

  for (file= m_file+1; *file; file++)
  {
    uint tmp= ((*file)->*operator_func)();
    set_if_smaller(min_of_the_max, tmp);
  }
  return min_of_the_max;
}


uint ha_partition::max_supported_key_parts() const
{
  return min_of_the_max_uint(&handler::max_supported_key_parts);
}


uint ha_partition::max_supported_key_length() const
{
  return min_of_the_max_uint(&handler::max_supported_key_length);
}


uint ha_partition::max_supported_key_part_length() const
{
  return min_of_the_max_uint(&handler::max_supported_key_part_length);
}


uint ha_partition::max_supported_record_length() const
{
  return min_of_the_max_uint(&handler::max_supported_record_length);
}


uint ha_partition::max_supported_keys() const
{
  return min_of_the_max_uint(&handler::max_supported_keys);
}


uint ha_partition::extra_rec_buf_length() const
{
  handler **file;
  uint max= (*m_file)->extra_rec_buf_length();

  for (file= m_file, file++; *file; file++)
    if (max < (*file)->extra_rec_buf_length())
      max= (*file)->extra_rec_buf_length();
  return max;
}


uint ha_partition::min_record_length(uint options) const
{
  handler **file;
  uint max= (*m_file)->min_record_length(options);

  for (file= m_file, file++; *file; file++)
    if (max < (*file)->min_record_length(options))
      max= (*file)->min_record_length(options);
  return max;
}


/****************************************************************************
                MODULE compare records
****************************************************************************/
/*
  Compare two positions

  SYNOPSIS
    cmp_ref()
    ref1                   First position
    ref2                   Second position

  RETURN VALUE
    <0                     ref1 < ref2
    0                      Equal
    >0                     ref1 > ref2

  DESCRIPTION
    We get two references and need to check if those records are the same.
    If they belong to different partitions we decide that they are not
    the same record. Otherwise we use the particular handler to decide if
    they are the same. Sort in partition id order if not equal.
*/

int ha_partition::cmp_ref(const uchar *ref1, const uchar *ref2)
{
  uint part_id;
  my_ptrdiff_t diff1, diff2;
  handler *file;
  DBUG_ENTER("ha_partition::cmp_ref");

  if ((ref1[0] == ref2[0]) && (ref1[1] == ref2[1]))
  {
    part_id= uint2korr(ref1);
    file= m_file[part_id];
    DBUG_ASSERT(part_id < m_tot_parts);
    DBUG_RETURN(file->cmp_ref((ref1 + PARTITION_BYTES_IN_POS),
                              (ref2 + PARTITION_BYTES_IN_POS)));
  }
  diff1= ref2[1] - ref1[1];
  diff2= ref2[0] - ref1[0];
  if (diff1 > 0)
  {
    DBUG_RETURN(-1);
  }
  if (diff1 < 0)
  {
    DBUG_RETURN(+1);
  }
  if (diff2 > 0)
  {
    DBUG_RETURN(-1);
  }
  DBUG_RETURN(+1);
}


/****************************************************************************
                MODULE auto increment
****************************************************************************/


int ha_partition::reset_auto_increment(ulonglong value)
{
  handler **file= m_file;
  int res;
  DBUG_ENTER("ha_partition::reset_auto_increment");
  lock_auto_increment();
  part_share->auto_inc_initialized= false;
  part_share->next_auto_inc_val= 0;
  do
  {
    if ((res= (*file)->ha_reset_auto_increment(value)) != 0)
      break;
  } while (*(++file));
  unlock_auto_increment();
  DBUG_RETURN(res);
}


void ha_partition::get_auto_increment(ulonglong offset, ulonglong increment,
                                      ulonglong nb_desired_values,
                                      ulonglong *first_value,
                                      ulonglong *nb_reserved_values)
{
  DBUG_ENTER("ha_partition::get_auto_increment");
  DBUG_PRINT("info", ("offset: %lu inc: %lu desired_values: %lu "
                      "first_value: %lu", (ulong) offset, (ulong) increment,
                      (ulong) nb_desired_values, (ulong) *first_value));
  DBUG_ASSERT(increment && nb_desired_values);
  *first_value= 0;
  if (table->s->next_number_keypart)
  {
    /*
      next_number_keypart is != 0 if the auto_increment column is a secondary
      column in the index (it is allowed in MyISAM)
    */
    DBUG_PRINT("info", ("next_number_keypart != 0"));
    ulonglong nb_reserved_values_part;
    ulonglong first_value_part, max_first_value;
    handler **file= m_file;
    first_value_part= max_first_value= *first_value;
    /* Must lock and find highest value among all partitions. */
    lock_auto_increment();
    do
    {
      /* Only nb_desired_values = 1 makes sense */
      (*file)->get_auto_increment(offset, increment, 1,
                                 &first_value_part, &nb_reserved_values_part);
      if (first_value_part == ULONGLONG_MAX) // error in one partition
      {
        *first_value= first_value_part;
        /* log that the error was between table/partition handler */
        sql_print_error("Partition failed to reserve auto_increment value");
        unlock_auto_increment();
        DBUG_VOID_RETURN;
      }
      DBUG_PRINT("info", ("first_value_part: %lu", (ulong) first_value_part));
      set_if_bigger(max_first_value, first_value_part);
    } while (*(++file));
    *first_value= max_first_value;
    *nb_reserved_values= 1;
    unlock_auto_increment();
  }
  else
  {
    THD *thd= ha_thd();
    /*
      This is initialized in the beginning of the first write_row call.
    */
    DBUG_ASSERT(part_share->auto_inc_initialized);
    /*
      Get a lock for handling the auto_increment in part_share
      for avoiding two concurrent statements getting the same number.
    */ 

    lock_auto_increment();

    /*
      In a multi-row insert statement like INSERT SELECT and LOAD DATA
      where the number of candidate rows to insert is not known in advance
      we must hold a lock/mutex for the whole statement if we have statement
      based replication. Because the statement-based binary log contains
      only the first generated value used by the statement, and slaves assumes
      all other generated values used by this statement were consecutive to
      this first one, we must exclusively lock the generator until the statement
      is done.
    */
    if (!auto_increment_safe_stmt_log_lock &&
        thd->lex->sql_command != SQLCOM_INSERT &&
        mysql_bin_log.is_open() &&
        !thd->is_current_stmt_binlog_format_row() &&
        (thd->variables.option_bits & OPTION_BIN_LOG))
    {
      DBUG_PRINT("info", ("locking auto_increment_safe_stmt_log_lock"));
      auto_increment_safe_stmt_log_lock= TRUE;
    }

    /* this gets corrected (for offset/increment) in update_auto_increment */
    *first_value= part_share->next_auto_inc_val;
    part_share->next_auto_inc_val+= nb_desired_values * increment;

    unlock_auto_increment();
    DBUG_PRINT("info", ("*first_value: %lu", (ulong) *first_value));
    *nb_reserved_values= nb_desired_values;
  }
  DBUG_VOID_RETURN;
}

void ha_partition::release_auto_increment()
{
  DBUG_ENTER("ha_partition::release_auto_increment");

  if (table->s->next_number_keypart)
  {
    uint i;
    for (i= bitmap_get_first_set(&m_part_info->lock_partitions);
         i < m_tot_parts;
         i= bitmap_get_next_set(&m_part_info->lock_partitions, i))
    {
      m_file[i]->ha_release_auto_increment();
    }
  }
  else if (next_insert_id)
  {
    ulonglong next_auto_inc_val;
    lock_auto_increment();
    next_auto_inc_val= part_share->next_auto_inc_val;
    /*
      If the current auto_increment values is lower than the reserved
      value, and the reserved value was reserved by this thread,
      we can lower the reserved value.
    */
    if (next_insert_id < next_auto_inc_val &&
        auto_inc_interval_for_cur_row.maximum() >= next_auto_inc_val)
    {
      THD *thd= ha_thd();
      /*
        Check that we do not lower the value because of a failed insert
        with SET INSERT_ID, i.e. forced/non generated values.
      */
      if (thd->auto_inc_intervals_forced.maximum() < next_insert_id)
        part_share->next_auto_inc_val= next_insert_id;
    }
    DBUG_PRINT("info", ("part_share->next_auto_inc_val: %lu",
                        (ulong) part_share->next_auto_inc_val));

    /* Unlock the multi row statement lock taken in get_auto_increment */
    if (auto_increment_safe_stmt_log_lock)
    {
      auto_increment_safe_stmt_log_lock= FALSE;
      DBUG_PRINT("info", ("unlocking auto_increment_safe_stmt_log_lock"));
    }

    unlock_auto_increment();
  }
  DBUG_VOID_RETURN;
}

/****************************************************************************
                MODULE initialize handler for HANDLER call
****************************************************************************/

void ha_partition::init_table_handle_for_HANDLER()
{
  return;
}


uint ha_partition::checksum() const
{
  ha_checksum sum= 0;

  DBUG_ENTER("ha_partition::checksum");
  if ((table_flags() & HA_HAS_CHECKSUM))
  {
    handler **file= m_file;
    do
    {
      sum+= (*file)->checksum();
    } while (*(++file));
  }
  DBUG_RETURN(sum);
}


/****************************************************************************
                MODULE enable/disable indexes
****************************************************************************/

/*
  Disable indexes for a while
  SYNOPSIS
    disable_indexes()
    mode                      Mode
  RETURN VALUES
    0                         Success
    != 0                      Error
*/

int ha_partition::disable_indexes(uint mode)
{
  handler **file;
  int error= 0;

  DBUG_ASSERT(bitmap_is_set_all(&(m_part_info->lock_partitions)));
  for (file= m_file; *file; file++)
  {
    if ((error= (*file)->ha_disable_indexes(mode)))
      break;
  }
  return error;
}


/*
  Enable indexes again
  SYNOPSIS
    enable_indexes()
    mode                      Mode
  RETURN VALUES
    0                         Success
    != 0                      Error
*/

int ha_partition::enable_indexes(uint mode)
{
  handler **file;
  int error= 0;

  DBUG_ASSERT(bitmap_is_set_all(&(m_part_info->lock_partitions)));
  for (file= m_file; *file; file++)
  {
    if ((error= (*file)->ha_enable_indexes(mode)))
      break;
  }
  return error;
}


/*
  Check if indexes are disabled
  SYNOPSIS
    indexes_are_disabled()

  RETURN VALUES
    0                      Indexes are enabled
    != 0                   Indexes are disabled
*/

int ha_partition::indexes_are_disabled(void)
{
  handler **file;
  int error= 0;

  DBUG_ASSERT(bitmap_is_set_all(&(m_part_info->lock_partitions)));
  for (file= m_file; *file; file++)
  {
    if ((error= (*file)->indexes_are_disabled()))
      break;
  }
  return error;
}


int ha_partition::check_misplaced_rows(uint read_part_id, bool repair)
{
  int result= 0;
  uint32 correct_part_id;
  longlong func_value;
  longlong num_misplaced_rows= 0;

  DBUG_ENTER("ha_partition::check_misplaced_rows");

  DBUG_ASSERT(m_file);

  if (repair)
  {
    /* We must read the full row, if we need to move it! */
    bitmap_set_all(table->read_set);
    bitmap_set_all(table->write_set);
  }
  else
  {
    /* Only need to read the partitioning fields. */
    bitmap_union(table->read_set, &m_part_info->full_part_field_set);
  }

  if ((result= m_file[read_part_id]->ha_rnd_init(1)))
    DBUG_RETURN(result);

  while (true)
  {
    if ((result= m_file[read_part_id]->ha_rnd_next(m_rec0)))
    {
      if (result == HA_ERR_RECORD_DELETED)
        continue;
      if (result != HA_ERR_END_OF_FILE)
        break;

      if (num_misplaced_rows > 0)
      {
        print_admin_msg(ha_thd(), MI_MAX_MSG_BUF, "warning",
                        table_share->db.str, table->alias,
                        opt_op_name[REPAIR_PARTS],
                        "Moved %lld misplaced rows",
                        num_misplaced_rows);
      }
      /* End-of-file reached, all rows are now OK, reset result and break. */
      result= 0;
      break;
    }

    result= m_part_info->get_partition_id(m_part_info, &correct_part_id,
                                          &func_value);
    if (result)
      break;

    if (correct_part_id != read_part_id)
    {
      num_misplaced_rows++;
      if (!repair)
      {
        /* Check. */
        print_admin_msg(ha_thd(), MI_MAX_MSG_BUF, "error",
                        table_share->db.str, table->alias,
                        opt_op_name[CHECK_PARTS],
                        "Found a misplaced row");
        /* Break on first misplaced row! */
        result= HA_ADMIN_NEEDS_UPGRADE;
        break;
      }
      else
      {
        DBUG_PRINT("info", ("Moving row from partition %d to %d",
                            read_part_id, correct_part_id));

        /*
          Insert row into correct partition. Notice that there are no commit
          for every N row, so the repair will be one large transaction!
        */
        if ((result= m_file[correct_part_id]->ha_write_row(m_rec0)))
        {
          /*
            We have failed to insert a row, it might have been a duplicate!
          */
          char buf[MAX_KEY_LENGTH];
          String str(buf,sizeof(buf),system_charset_info);
          str.length(0);
          if (result == HA_ERR_FOUND_DUPP_KEY)
          {
            str.append("Duplicate key found, "
                       "please update or delete the record:\n");
            result= HA_ADMIN_CORRUPT;
          }
          m_err_rec= NULL;
          append_row_to_str(str);

          /*
            If the engine supports transactions, the failure will be
            rollbacked.
          */
          if (!m_file[correct_part_id]->has_transactions())
          {
            /* Log this error, so the DBA can notice it and fix it! */
            sql_print_error("Table '%-192s' failed to move/insert a row"
                            " from part %d into part %d:\n%s",
                            table->s->table_name.str,
                            read_part_id,
                            correct_part_id,
                            str.c_ptr_safe());
          }
          print_admin_msg(ha_thd(), MI_MAX_MSG_BUF, "error",
                          table_share->db.str, table->alias,
                          opt_op_name[REPAIR_PARTS],
                          "Failed to move/insert a row"
                          " from part %d into part %d:\n%s",
                          read_part_id,
                          correct_part_id,
                          str.c_ptr_safe());
          break;
        }

        /* Delete row from wrong partition. */
        if ((result= m_file[read_part_id]->ha_delete_row(m_rec0)))
        {
          if (m_file[correct_part_id]->has_transactions())
            break;
          /*
            We have introduced a duplicate, since we failed to remove it
            from the wrong partition.
          */
          char buf[MAX_KEY_LENGTH];
          String str(buf,sizeof(buf),system_charset_info);
          str.length(0);
          m_err_rec= NULL;
          append_row_to_str(str);

          /* Log this error, so the DBA can notice it and fix it! */
          sql_print_error("Table '%-192s': Delete from part %d failed with"
                          " error %d. But it was already inserted into"
                          " part %d, when moving the misplaced row!"
                          "\nPlease manually fix the duplicate row:\n%s",
                          table->s->table_name.str,
                          read_part_id,
                          result,
                          correct_part_id,
                          str.c_ptr_safe());
          break;
        }
      }
    }
  }

  int tmp_result= m_file[read_part_id]->ha_rnd_end();
  DBUG_RETURN(result ? result : tmp_result);
}


#define KEY_PARTITIONING_CHANGED_STR \
  "KEY () partitioning changed, please run:\n" \
  "ALTER TABLE %s.%s ALGORITHM = INPLACE %s"

int ha_partition::check_for_upgrade(HA_CHECK_OPT *check_opt)
{
  int error= HA_ADMIN_NEEDS_CHECK;
  DBUG_ENTER("ha_partition::check_for_upgrade");

  /*
    This is called even without FOR UPGRADE,
    if the .frm version is lower than the current version.
    In that case return that it needs checking!
  */
  if (!(check_opt->sql_flags & TT_FOR_UPGRADE))
    DBUG_RETURN(error);

  /*
    Partitions will be checked for during their ha_check!

    Check if KEY (sub)partitioning was used and any field's hash calculation
    differs from 5.1, see bug#14521864.
  */
  if (table->s->mysql_version < 50503 &&              // 5.1 table (<5.5.3)
      ((m_part_info->part_type == HASH_PARTITION &&   // KEY partitioned
        m_part_info->list_of_part_fields) ||
       (m_is_sub_partitioned &&                       // KEY subpartitioned
        m_part_info->list_of_subpart_fields)))
  {
    Field **field;
    if (m_is_sub_partitioned)
    {
      field= m_part_info->subpart_field_array;
    }
    else
    {
      field= m_part_info->part_field_array;
    }
    for (; *field; field++)
    {
      switch ((*field)->real_type()) {
      case MYSQL_TYPE_TINY:
      case MYSQL_TYPE_SHORT:
      case MYSQL_TYPE_LONG:
      case MYSQL_TYPE_FLOAT:
      case MYSQL_TYPE_DOUBLE:
      case MYSQL_TYPE_NEWDECIMAL:
      case MYSQL_TYPE_TIMESTAMP:
      case MYSQL_TYPE_LONGLONG:
      case MYSQL_TYPE_INT24:
      case MYSQL_TYPE_TIME:
      case MYSQL_TYPE_DATETIME:
      case MYSQL_TYPE_YEAR:
      case MYSQL_TYPE_NEWDATE:
      case MYSQL_TYPE_ENUM:
      case MYSQL_TYPE_SET:
        {
          THD *thd= ha_thd();
          char *part_buf;
          String db_name, table_name;
          uint part_buf_len;
          bool skip_generation= false;
          partition_info::enum_key_algorithm old_algorithm;
          old_algorithm= m_part_info->key_algorithm;
          error= HA_ADMIN_FAILED;
          append_identifier(ha_thd(), &db_name, table_share->db.str,
                            table_share->db.length);
          append_identifier(ha_thd(), &table_name, table_share->table_name.str,
                            table_share->table_name.length);
          if (m_part_info->key_algorithm != partition_info::KEY_ALGORITHM_NONE)
          {
            /*
              Only possible when someone tampered with .frm files,
              like during tests :)
            */
            skip_generation= true;
          }
          m_part_info->key_algorithm= partition_info::KEY_ALGORITHM_51;
          if (skip_generation ||
              !(part_buf= generate_partition_syntax(m_part_info,
                                                    &part_buf_len,
                                                    true,
                                                    true,
                                                    NULL,
                                                    NULL,
                                                    NULL)) ||
              print_admin_msg(thd, SQL_ADMIN_MSG_TEXT_SIZE + 1, "error",
                              table_share->db.str,
                              table->alias,
                              opt_op_name[CHECK_PARTS],
                              KEY_PARTITIONING_CHANGED_STR,
                              db_name.c_ptr_safe(),
                              table_name.c_ptr_safe(),
                              part_buf))
          {
            /* Error creating admin message (too long string?). */
            print_admin_msg(thd, MI_MAX_MSG_BUF, "error",
                            table_share->db.str, table->alias,
                            opt_op_name[CHECK_PARTS],
                            KEY_PARTITIONING_CHANGED_STR,
                            db_name.c_ptr_safe(), table_name.c_ptr_safe(),
                            "<old partition clause>, but add ALGORITHM = 1"
                            " between 'KEY' and '(' to change the metadata"
                            " without the need of a full table rebuild.");
          }
          m_part_info->key_algorithm= old_algorithm;
          DBUG_RETURN(error);
        }
      default:
        /* Not affected! */
        ;
      }
    }
  }

  DBUG_RETURN(error);
}


struct st_mysql_storage_engine partition_storage_engine=
{ MYSQL_HANDLERTON_INTERFACE_VERSION };

mysql_declare_plugin(partition)
{
  MYSQL_STORAGE_ENGINE_PLUGIN,
  &partition_storage_engine,
  "partition",
  "Mikael Ronstrom, MySQL AB",
  "Partition Storage Engine Helper",
  PLUGIN_LICENSE_GPL,
  partition_initialize, /* Plugin Init */
  NULL, /* Plugin Deinit */
  0x0100, /* 1.0 */
  NULL,                       /* status variables                */
  NULL,                       /* system variables                */
  NULL,                       /* config options                  */
  0,                          /* flags                           */
}
mysql_declare_plugin_end;

#endif