handler.cc

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/* Copyright (c) 2000, 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 Street, Suite 500, Boston, MA 02110-1335 USA */

#include "binlog.h"
#include "sql_priv.h"
#include "unireg.h"
#include "rpl_handler.h"
#include "sql_cache.h"                   // query_cache, query_cache_*
#include "key.h"     // key_copy, key_unpack, key_cmp_if_same, key_cmp
#include "sql_table.h"                   // build_table_filename
#include "sql_parse.h"                          // check_stack_overrun
#include "sql_acl.h"            // SUPER_ACL
#include "sql_base.h"           // free_io_cache
#include "discover.h"           // writefrm
#include "log_event.h"          // *_rows_log_event
#include "rpl_filter.h"
#include <myisampack.h>
#include "transaction.h"
#include <errno.h>
#include "probes_mysql.h"
#include <mysql/psi/mysql_table.h>
#include "debug_sync.h"         // DEBUG_SYNC
#include <my_bit.h>
#include <list>

#ifdef WITH_PARTITION_STORAGE_ENGINE
#include "ha_partition.h"
#endif

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

// This is a temporary backporting fix.
#ifndef HAVE_LOG2
/*
  This will be slightly slower and perhaps a tiny bit less accurate than
  doing it the IEEE754 way but log2() should be available on C99 systems.
*/
inline double log2(double x)
{
  return (log(x) / M_LN2);
}
#endif

/*
  While we have legacy_db_type, we have this array to
  check for dups and to find handlerton from legacy_db_type.
  Remove when legacy_db_type is finally gone
*/
st_plugin_int *hton2plugin[MAX_HA];

static handlerton *installed_htons[128];

#define BITMAP_STACKBUF_SIZE (128/8)

KEY_CREATE_INFO default_key_create_info=
  { HA_KEY_ALG_UNDEF, 0, {NullS, 0}, {NullS, 0}, true };

/* number of entries in handlertons[] */
ulong total_ha= 0;
/* number of storage engines (from handlertons[]) that support 2pc */
ulong total_ha_2pc= 0;
/* size of savepoint storage area (see ha_init) */
ulong savepoint_alloc_size= 0;

static const LEX_STRING sys_table_aliases[]=
{
  { C_STRING_WITH_LEN("INNOBASE") },  { C_STRING_WITH_LEN("INNODB") },
  { C_STRING_WITH_LEN("NDB") },       { C_STRING_WITH_LEN("NDBCLUSTER") },
  { C_STRING_WITH_LEN("HEAP") },      { C_STRING_WITH_LEN("MEMORY") },
  { C_STRING_WITH_LEN("MERGE") },     { C_STRING_WITH_LEN("MRG_MYISAM") },
  {NullS, 0}
};

const char *ha_row_type[] = {
  "", "FIXED", "DYNAMIC", "COMPRESSED", "REDUNDANT", "COMPACT",
  /* Reserved to be "PAGE" in future versions */ "?",
  "?","?","?"
};

const char *tx_isolation_names[] =
{ "READ-UNCOMMITTED", "READ-COMMITTED", "REPEATABLE-READ", "SERIALIZABLE",
  NullS};
TYPELIB tx_isolation_typelib= {array_elements(tx_isolation_names)-1,"",
                               tx_isolation_names, NULL};

#ifndef DBUG_OFF

const char *ha_legacy_type_name(legacy_db_type legacy_type)
{
  switch (legacy_type)
  {
  case DB_TYPE_UNKNOWN:
    return "DB_TYPE_UNKNOWN";
  case DB_TYPE_DIAB_ISAM:
    return "DB_TYPE_DIAB_ISAM";
  case DB_TYPE_HASH:
    return "DB_TYPE_HASH";
  case DB_TYPE_MISAM:
    return "DB_TYPE_MISAM";
  case DB_TYPE_PISAM:
    return "DB_TYPE_PISAM";
  case DB_TYPE_RMS_ISAM:
    return "DB_TYPE_RMS_ISAM";
  case DB_TYPE_HEAP:
    return "DB_TYPE_HEAP";
  case DB_TYPE_ISAM:
    return "DB_TYPE_ISAM";
  case DB_TYPE_MRG_ISAM:
    return "DB_TYPE_MRG_ISAM";
  case DB_TYPE_MYISAM:
    return "DB_TYPE_MYISAM";
  case DB_TYPE_MRG_MYISAM:
    return "DB_TYPE_MRG_MYISAM";
  case DB_TYPE_BERKELEY_DB:
    return "DB_TYPE_BERKELEY_DB";
  case DB_TYPE_INNODB:
    return "DB_TYPE_INNODB";
  case DB_TYPE_GEMINI:
    return "DB_TYPE_GEMINI";
  case DB_TYPE_NDBCLUSTER:
    return "DB_TYPE_NDBCLUSTER";
  case DB_TYPE_EXAMPLE_DB:
    return "DB_TYPE_EXAMPLE_DB";
  case DB_TYPE_ARCHIVE_DB:
    return "DB_TYPE_ARCHIVE_DB";
  case DB_TYPE_CSV_DB:
    return "DB_TYPE_CSV_DB";
  case DB_TYPE_FEDERATED_DB:
    return "DB_TYPE_FEDERATED_DB";
  case DB_TYPE_BLACKHOLE_DB:
    return "DB_TYPE_BLACKHOLE_DB";
  case DB_TYPE_PARTITION_DB:
    return "DB_TYPE_PARTITION_DB";
  case DB_TYPE_BINLOG:
    return "DB_TYPE_BINLOG";
  case DB_TYPE_SOLID:
    return "DB_TYPE_SOLID";
  case DB_TYPE_PBXT:
    return "DB_TYPE_PBXT";
  case DB_TYPE_TABLE_FUNCTION:
    return "DB_TYPE_TABLE_FUNCTION";
  case DB_TYPE_MEMCACHE:
    return "DB_TYPE_MEMCACHE";
  case DB_TYPE_FALCON:
    return "DB_TYPE_FALCON";
  case DB_TYPE_MARIA:
    return "DB_TYPE_MARIA";
  case DB_TYPE_PERFORMANCE_SCHEMA:
    return "DB_TYPE_PERFORMANCE_SCHEMA";
  default:
    return "DB_TYPE_DYNAMIC";
  }
}
#endif

const char* mysqld_system_database= "mysql";

// System tables that belong to mysqld_system_database.
st_system_tablename mysqld_system_tables[]= {
  {mysqld_system_database, "db"},
  {mysqld_system_database, "user"},
  {mysqld_system_database, "host"},
  {mysqld_system_database, "func"},
  {mysqld_system_database, "proc"},
  {mysqld_system_database, "event"},
  {mysqld_system_database, "plugin"},
  {mysqld_system_database, "servers"},
  {mysqld_system_database, "procs_priv"},
  {mysqld_system_database, "tables_priv"},
  {mysqld_system_database, "proxies_priv"},
  {mysqld_system_database, "columns_priv"},
  {mysqld_system_database, "time_zone"},
  {mysqld_system_database, "time_zone_name"},
  {mysqld_system_database, "time_zone_leap_second"},
  {mysqld_system_database, "time_zone_transition"},
  {mysqld_system_database, "time_zone_transition_type"},
  {mysqld_system_database, "help_category"},
  {mysqld_system_database, "help_keyword"},
  {mysqld_system_database, "help_relation"},
  {mysqld_system_database, "help_topic"},
  {(const char *)NULL, (const char *)NULL} /* This must be at the end */
};

static const char **known_system_databases= NULL;
static const char **ha_known_system_databases();

// Called for each SE to get SE specific system database.
static my_bool system_databases_handlerton(THD *unused, plugin_ref plugin,
                                           void *arg);

// Called for each SE to check if given db.table_name is a system table.
static my_bool check_engine_system_table_handlerton(THD *unused,
                                                    plugin_ref plugin,
                                                    void *arg);
struct st_sys_tbl_chk_params
{
  const char *db;                             // IN param
  const char *table_name;                     // IN param
  bool is_sql_layer_system_table;             // IN param
  legacy_db_type db_type;                     // IN param

  enum enum_sys_tbl_chk_status
  {
    // db.table_name is not a supported system table.
    NOT_KNOWN_SYSTEM_TABLE,
    /*
      db.table_name is a system table,
      but may not be supported by SE.
    */
    KNOWN_SYSTEM_TABLE,
    /*
      db.table_name is a system table,
      and is supported by SE.
    */
    SUPPORTED_SYSTEM_TABLE
  } status;                                    // OUT param
};


static plugin_ref ha_default_plugin(THD *thd)
{
  if (thd->variables.table_plugin)
    return thd->variables.table_plugin;
  return my_plugin_lock(thd, &global_system_variables.table_plugin);
}


handlerton *ha_default_handlerton(THD *thd)
{
  plugin_ref plugin= ha_default_plugin(thd);
  DBUG_ASSERT(plugin);
  handlerton *hton= plugin_data(plugin, handlerton*);
  DBUG_ASSERT(hton);
  return hton;
}


static plugin_ref ha_default_temp_plugin(THD *thd)
{
  if (thd->variables.temp_table_plugin)
    return thd->variables.temp_table_plugin;
  return my_plugin_lock(thd, &global_system_variables.temp_table_plugin);
}


handlerton *ha_default_temp_handlerton(THD *thd)
{
  plugin_ref plugin= ha_default_temp_plugin(thd);
  DBUG_ASSERT(plugin);
  handlerton *hton= plugin_data(plugin, handlerton*);
  DBUG_ASSERT(hton);
  return hton;
}


plugin_ref ha_resolve_by_name(THD *thd, const LEX_STRING *name, 
                              bool is_temp_table)
{
  const LEX_STRING *table_alias;
  plugin_ref plugin;

redo:
  /* my_strnncoll is a macro and gcc doesn't do early expansion of macro */
  if (thd && !my_charset_latin1.coll->strnncoll(&my_charset_latin1,
                           (const uchar *)name->str, name->length,
                           (const uchar *)STRING_WITH_LEN("DEFAULT"), 0))
    return is_temp_table ? 
      ha_default_plugin(thd) : ha_default_temp_plugin(thd);

  if ((plugin= my_plugin_lock_by_name(thd, name, MYSQL_STORAGE_ENGINE_PLUGIN)))
  {
    handlerton *hton= plugin_data(plugin, handlerton *);
    if (!(hton->flags & HTON_NOT_USER_SELECTABLE))
      return plugin;
      
    /*
      unlocking plugin immediately after locking is relatively low cost.
    */
    plugin_unlock(thd, plugin);
  }

  /*
    We check for the historical aliases.
  */
  for (table_alias= sys_table_aliases; table_alias->str; table_alias+= 2)
  {
    if (!my_strnncoll(&my_charset_latin1,
                      (const uchar *)name->str, name->length,
                      (const uchar *)table_alias->str, table_alias->length))
    {
      name= table_alias + 1;
      goto redo;
    }
  }

  return NULL;
}


plugin_ref ha_lock_engine(THD *thd, const handlerton *hton)
{
  if (hton)
  {
    st_plugin_int **plugin= hton2plugin + hton->slot;
    
#ifdef DBUG_OFF
    return my_plugin_lock(thd, plugin);
#else
    return my_plugin_lock(thd, &plugin);
#endif
  }
  return NULL;
}


handlerton *ha_resolve_by_legacy_type(THD *thd, enum legacy_db_type db_type)
{
  plugin_ref plugin;
  switch (db_type) {
  case DB_TYPE_DEFAULT:
    return ha_default_handlerton(thd);
  default:
    if (db_type > DB_TYPE_UNKNOWN && db_type < DB_TYPE_DEFAULT &&
        (plugin= ha_lock_engine(thd, installed_htons[db_type])))
      return plugin_data(plugin, handlerton*);
    /* fall through */
  case DB_TYPE_UNKNOWN:
    return NULL;
  }
}


handlerton *ha_checktype(THD *thd, enum legacy_db_type database_type,
                          bool no_substitute, bool report_error)
{
  handlerton *hton= ha_resolve_by_legacy_type(thd, database_type);
  if (ha_storage_engine_is_enabled(hton))
    return hton;

  if (no_substitute)
  {
    if (report_error)
    {
      const char *engine_name= ha_resolve_storage_engine_name(hton);
      my_error(ER_FEATURE_DISABLED,MYF(0),engine_name,engine_name);
    }
    return NULL;
  }

  (void) RUN_HOOK(transaction, after_rollback, (thd, FALSE));

  switch (database_type) {
  case DB_TYPE_MRG_ISAM:
    return ha_resolve_by_legacy_type(thd, DB_TYPE_MRG_MYISAM);
  default:
    break;
  }

  return ha_default_handlerton(thd);
} /* ha_checktype */


handler *get_new_handler(TABLE_SHARE *share, MEM_ROOT *alloc,
                         handlerton *db_type)
{
  handler *file;
  DBUG_ENTER("get_new_handler");
  DBUG_PRINT("enter", ("alloc: 0x%lx", (long) alloc));

  if (db_type && db_type->state == SHOW_OPTION_YES && db_type->create)
  {
    if ((file= db_type->create(db_type, share, alloc)))
      file->init();
    DBUG_RETURN(file);
  }
  /*
    Try the default table type
    Here the call to current_thd() is ok as we call this function a lot of
    times but we enter this branch very seldom.
  */
  DBUG_RETURN(get_new_handler(share, alloc, ha_default_handlerton(current_thd)));
}


#ifdef WITH_PARTITION_STORAGE_ENGINE
handler *get_ha_partition(partition_info *part_info)
{
  ha_partition *partition;
  DBUG_ENTER("get_ha_partition");
  if ((partition= new ha_partition(partition_hton, part_info)))
  {
    if (partition->initialize_partition(current_thd->mem_root))
    {
      delete partition;
      partition= 0;
    }
    else
      partition->init();
  }
  else
  {
    my_error(ER_OUTOFMEMORY, MYF(ME_FATALERROR), 
             static_cast<int>(sizeof(ha_partition)));
  }
  DBUG_RETURN(((handler*) partition));
}
#endif


static const char **handler_errmsgs;

C_MODE_START
static const char **get_handler_errmsgs()
{
  return handler_errmsgs;
}
C_MODE_END


int ha_init_errors(void)
{
#define SETMSG(nr, msg) handler_errmsgs[(nr) - HA_ERR_FIRST]= (msg)

  /* Allocate a pointer array for the error message strings. */
  /* Zerofill it to avoid uninitialized gaps. */
  if (! (handler_errmsgs= (const char**) my_malloc(HA_ERR_ERRORS * sizeof(char*),
                                                   MYF(MY_WME | MY_ZEROFILL))))
    return 1;

  /* Set the dedicated error messages. */
  SETMSG(HA_ERR_KEY_NOT_FOUND,          ER_DEFAULT(ER_KEY_NOT_FOUND));
  SETMSG(HA_ERR_FOUND_DUPP_KEY,         ER_DEFAULT(ER_DUP_KEY));
  SETMSG(HA_ERR_RECORD_CHANGED,         "Update wich is recoverable");
  SETMSG(HA_ERR_WRONG_INDEX,            "Wrong index given to function");
  SETMSG(HA_ERR_CRASHED,                ER_DEFAULT(ER_NOT_KEYFILE));
  SETMSG(HA_ERR_WRONG_IN_RECORD,        ER_DEFAULT(ER_CRASHED_ON_USAGE));
  SETMSG(HA_ERR_OUT_OF_MEM,             "Table handler out of memory");
  SETMSG(HA_ERR_NOT_A_TABLE,            "Incorrect file format '%.64s'");
  SETMSG(HA_ERR_WRONG_COMMAND,          "Command not supported");
  SETMSG(HA_ERR_OLD_FILE,               ER_DEFAULT(ER_OLD_KEYFILE));
  SETMSG(HA_ERR_NO_ACTIVE_RECORD,       "No record read in update");
  SETMSG(HA_ERR_RECORD_DELETED,         "Intern record deleted");
  SETMSG(HA_ERR_RECORD_FILE_FULL,       ER_DEFAULT(ER_RECORD_FILE_FULL));
  SETMSG(HA_ERR_INDEX_FILE_FULL,        "No more room in index file '%.64s'");
  SETMSG(HA_ERR_END_OF_FILE,            "End in next/prev/first/last");
  SETMSG(HA_ERR_UNSUPPORTED,            ER_DEFAULT(ER_ILLEGAL_HA));
  SETMSG(HA_ERR_TO_BIG_ROW,             "Too big row");
  SETMSG(HA_WRONG_CREATE_OPTION,        "Wrong create option");
  SETMSG(HA_ERR_FOUND_DUPP_UNIQUE,      ER_DEFAULT(ER_DUP_UNIQUE));
  SETMSG(HA_ERR_UNKNOWN_CHARSET,        "Can't open charset");
  SETMSG(HA_ERR_WRONG_MRG_TABLE_DEF,    ER_DEFAULT(ER_WRONG_MRG_TABLE));
  SETMSG(HA_ERR_CRASHED_ON_REPAIR,      ER_DEFAULT(ER_CRASHED_ON_REPAIR));
  SETMSG(HA_ERR_CRASHED_ON_USAGE,       ER_DEFAULT(ER_CRASHED_ON_USAGE));
  SETMSG(HA_ERR_LOCK_WAIT_TIMEOUT,      ER_DEFAULT(ER_LOCK_WAIT_TIMEOUT));
  SETMSG(HA_ERR_LOCK_TABLE_FULL,        ER_DEFAULT(ER_LOCK_TABLE_FULL));
  SETMSG(HA_ERR_READ_ONLY_TRANSACTION,  ER_DEFAULT(ER_READ_ONLY_TRANSACTION));
  SETMSG(HA_ERR_LOCK_DEADLOCK,          ER_DEFAULT(ER_LOCK_DEADLOCK));
  SETMSG(HA_ERR_CANNOT_ADD_FOREIGN,     ER_DEFAULT(ER_CANNOT_ADD_FOREIGN));
  SETMSG(HA_ERR_NO_REFERENCED_ROW,      ER_DEFAULT(ER_NO_REFERENCED_ROW_2));
  SETMSG(HA_ERR_ROW_IS_REFERENCED,      ER_DEFAULT(ER_ROW_IS_REFERENCED_2));
  SETMSG(HA_ERR_NO_SAVEPOINT,           "No savepoint with that name");
  SETMSG(HA_ERR_NON_UNIQUE_BLOCK_SIZE,  "Non unique key block size");
  SETMSG(HA_ERR_NO_SUCH_TABLE,          "No such table: '%.64s'");
  SETMSG(HA_ERR_TABLE_EXIST,            ER_DEFAULT(ER_TABLE_EXISTS_ERROR));
  SETMSG(HA_ERR_NO_CONNECTION,          "Could not connect to storage engine");
  SETMSG(HA_ERR_TABLE_DEF_CHANGED,      ER_DEFAULT(ER_TABLE_DEF_CHANGED));
  SETMSG(HA_ERR_FOREIGN_DUPLICATE_KEY,  "FK constraint would lead to duplicate key");
  SETMSG(HA_ERR_TABLE_NEEDS_UPGRADE,    ER_DEFAULT(ER_TABLE_NEEDS_UPGRADE));
  SETMSG(HA_ERR_TABLE_READONLY,         ER_DEFAULT(ER_OPEN_AS_READONLY));
  SETMSG(HA_ERR_AUTOINC_READ_FAILED,    ER_DEFAULT(ER_AUTOINC_READ_FAILED));
  SETMSG(HA_ERR_AUTOINC_ERANGE,         ER_DEFAULT(ER_WARN_DATA_OUT_OF_RANGE));
  SETMSG(HA_ERR_TOO_MANY_CONCURRENT_TRXS, ER_DEFAULT(ER_TOO_MANY_CONCURRENT_TRXS));
  SETMSG(HA_ERR_INDEX_COL_TOO_LONG,     ER_DEFAULT(ER_INDEX_COLUMN_TOO_LONG));
  SETMSG(HA_ERR_INDEX_CORRUPT,          ER_DEFAULT(ER_INDEX_CORRUPT));
  SETMSG(HA_FTS_INVALID_DOCID,          "Invalid InnoDB FTS Doc ID");
  SETMSG(HA_ERR_TABLE_IN_FK_CHECK,      ER_DEFAULT(ER_TABLE_IN_FK_CHECK));
  SETMSG(HA_ERR_TABLESPACE_EXISTS,      "Tablespace already exists");
  SETMSG(HA_ERR_FTS_EXCEED_RESULT_CACHE_LIMIT,  "FTS query exceeds result cache limit");

  /* Register the error messages for use with my_error(). */
  return my_error_register(get_handler_errmsgs, HA_ERR_FIRST, HA_ERR_LAST);
}


static int ha_finish_errors(void)
{
  const char    **errmsgs;

  /* Allocate a pointer array for the error message strings. */
  if (! (errmsgs= my_error_unregister(HA_ERR_FIRST, HA_ERR_LAST)))
    return 1;
  my_free(errmsgs);
  return 0;
}


int ha_finalize_handlerton(st_plugin_int *plugin)
{
  handlerton *hton= (handlerton *)plugin->data;
  DBUG_ENTER("ha_finalize_handlerton");

  /* hton can be NULL here, if ha_initialize_handlerton() failed. */
  if (!hton)
    goto end;

  switch (hton->state)
  {
  case SHOW_OPTION_NO:
  case SHOW_OPTION_DISABLED:
    break;
  case SHOW_OPTION_YES:
    if (installed_htons[hton->db_type] == hton)
      installed_htons[hton->db_type]= NULL;
    break;
  };

  if (hton->panic)
    hton->panic(hton, HA_PANIC_CLOSE);

  if (plugin->plugin->deinit)
  {
    /*
      Today we have no defined/special behavior for uninstalling
      engine plugins.
    */
    DBUG_PRINT("info", ("Deinitializing plugin: '%s'", plugin->name.str));
    if (plugin->plugin->deinit(NULL))
    {
      DBUG_PRINT("warning", ("Plugin '%s' deinit function returned error.",
                             plugin->name.str));
    }
  }

  /*
    In case a plugin is uninstalled and re-installed later, it should
    reuse an array slot. Otherwise the number of uninstall/install
    cycles would be limited.
  */
  if (hton->slot != HA_SLOT_UNDEF)
  {
    /* Make sure we are not unpluging another plugin */
    DBUG_ASSERT(hton2plugin[hton->slot] == plugin);
    DBUG_ASSERT(hton->slot < MAX_HA);
    hton2plugin[hton->slot]= NULL;
  }

  my_free(hton);

 end:
  DBUG_RETURN(0);
}


int ha_initialize_handlerton(st_plugin_int *plugin)
{
  handlerton *hton;
  DBUG_ENTER("ha_initialize_handlerton");
  DBUG_PRINT("plugin", ("initialize plugin: '%s'", plugin->name.str));

  hton= (handlerton *)my_malloc(sizeof(handlerton),
                                MYF(MY_WME | MY_ZEROFILL));

  if (hton == NULL)
  {
    sql_print_error("Unable to allocate memory for plugin '%s' handlerton.",
                    plugin->name.str);
    goto err_no_hton_memory;
  }

  hton->slot= HA_SLOT_UNDEF;
  /* Historical Requirement */
  plugin->data= hton; // shortcut for the future
  if (plugin->plugin->init && plugin->plugin->init(hton))
  {
    sql_print_error("Plugin '%s' init function returned error.",
                    plugin->name.str);
    goto err;  
  }

  /*
    the switch below and hton->state should be removed when
    command-line options for plugins will be implemented
  */
  DBUG_PRINT("info", ("hton->state=%d", hton->state));
  switch (hton->state) {
  case SHOW_OPTION_NO:
    break;
  case SHOW_OPTION_YES:
    {
      uint tmp;
      ulong fslot;
      /* now check the db_type for conflict */
      if (hton->db_type <= DB_TYPE_UNKNOWN ||
          hton->db_type >= DB_TYPE_DEFAULT ||
          installed_htons[hton->db_type])
      {
        int idx= (int) DB_TYPE_FIRST_DYNAMIC;

        while (idx < (int) DB_TYPE_DEFAULT && installed_htons[idx])
          idx++;

        if (idx == (int) DB_TYPE_DEFAULT)
        {
          sql_print_warning("Too many storage engines!");
          goto err_deinit;
        }
        if (hton->db_type != DB_TYPE_UNKNOWN)
          sql_print_warning("Storage engine '%s' has conflicting typecode. "
                            "Assigning value %d.", plugin->plugin->name, idx);
        hton->db_type= (enum legacy_db_type) idx;
      }

      /*
        In case a plugin is uninstalled and re-installed later, it should
        reuse an array slot. Otherwise the number of uninstall/install
        cycles would be limited. So look for a free slot.
      */
      DBUG_PRINT("plugin", ("total_ha: %lu", total_ha));
      for (fslot= 0; fslot < total_ha; fslot++)
      {
        if (!hton2plugin[fslot])
          break;
      }
      if (fslot < total_ha)
        hton->slot= fslot;
      else
      {
        if (total_ha >= MAX_HA)
        {
          sql_print_error("Too many plugins loaded. Limit is %lu. "
                          "Failed on '%s'", (ulong) MAX_HA, plugin->name.str);
          goto err_deinit;
        }
        hton->slot= total_ha++;
      }
      installed_htons[hton->db_type]= hton;
      tmp= hton->savepoint_offset;
      hton->savepoint_offset= savepoint_alloc_size;
      savepoint_alloc_size+= tmp;
      hton2plugin[hton->slot]=plugin;
      if (hton->prepare)
        total_ha_2pc++;
      break;
    }
    /* fall through */
  default:
    hton->state= SHOW_OPTION_DISABLED;
    break;
  }
  
  /* 
    This is entirely for legacy. We will create a new "disk based" hton and a 
    "memory" hton which will be configurable longterm. We should be able to 
    remove partition and myisammrg.
  */
  switch (hton->db_type) {
  case DB_TYPE_HEAP:
    heap_hton= hton;
    break;
  case DB_TYPE_MYISAM:
    myisam_hton= hton;
    break;
  case DB_TYPE_PARTITION_DB:
    partition_hton= hton;
    break;
  default:
    break;
  };

  DBUG_RETURN(0);

err_deinit:
  /* 
    Let plugin do its inner deinitialization as plugin->init() 
    was successfully called before.
  */
  if (plugin->plugin->deinit)
    (void) plugin->plugin->deinit(NULL);
          
err:
  my_free(hton);
err_no_hton_memory:
  plugin->data= NULL;
  DBUG_RETURN(1);
}

int ha_init()
{
  int error= 0;
  DBUG_ENTER("ha_init");

  DBUG_ASSERT(total_ha < MAX_HA);
  /*
    Check if there is a transaction-capable storage engine besides the
    binary log (which is considered a transaction-capable storage engine in
    counting total_ha)
  */
  opt_using_transactions= total_ha>(ulong)opt_bin_log;
  savepoint_alloc_size+= sizeof(SAVEPOINT);

  /*
    Initialize system database name cache.
    This cache is used to do a quick check if a given
    db.tablename is a system table.
  */
  known_system_databases= ha_known_system_databases();

  DBUG_RETURN(error);
}

int ha_end()
{
  int error= 0;
  DBUG_ENTER("ha_end");


  /* 
    This should be eventualy based  on the graceful shutdown flag.
    So if flag is equal to HA_PANIC_CLOSE, the deallocate
    the errors.
  */
  if (ha_finish_errors())
    error= 1;

  DBUG_RETURN(error);
}

static my_bool dropdb_handlerton(THD *unused1, plugin_ref plugin,
                                 void *path)
{
  handlerton *hton= plugin_data(plugin, handlerton *);
  if (hton->state == SHOW_OPTION_YES && hton->drop_database)
    hton->drop_database(hton, (char *)path);
  return FALSE;
}


void ha_drop_database(char* path)
{
  plugin_foreach(NULL, dropdb_handlerton, MYSQL_STORAGE_ENGINE_PLUGIN, path);
}


static my_bool closecon_handlerton(THD *thd, plugin_ref plugin,
                                   void *unused)
{
  handlerton *hton= plugin_data(plugin, handlerton *);
  /*
    there's no need to rollback here as all transactions must
    be rolled back already
  */
  if (hton->state == SHOW_OPTION_YES && thd_get_ha_data(thd, hton))
  {
    if (hton->close_connection)
      hton->close_connection(hton, thd);
    /* make sure ha_data is reset and ha_data_lock is released */
    thd_set_ha_data(thd, hton, NULL);
  }
  return FALSE;
}


void ha_close_connection(THD* thd)
{
  plugin_foreach(thd, closecon_handlerton, MYSQL_STORAGE_ENGINE_PLUGIN, 0);
}

/* ========================================================================
 ======================= TRANSACTIONS ===================================*/

void trans_register_ha(THD *thd, bool all, handlerton *ht_arg)
{
  THD_TRANS *trans;
  Ha_trx_info *ha_info;
  DBUG_ENTER("trans_register_ha");
  DBUG_PRINT("enter",("%s", all ? "all" : "stmt"));

  if (all)
  {
    trans= &thd->transaction.all;
    thd->server_status|= SERVER_STATUS_IN_TRANS;
    if (thd->tx_read_only)
      thd->server_status|= SERVER_STATUS_IN_TRANS_READONLY;
    DBUG_PRINT("info", ("setting SERVER_STATUS_IN_TRANS"));
  }
  else
    trans= &thd->transaction.stmt;

  ha_info= thd->ha_data[ht_arg->slot].ha_info + (all ? 1 : 0);

  if (ha_info->is_started())
    DBUG_VOID_RETURN; /* already registered, return */

  ha_info->register_ha(trans, ht_arg);

  trans->no_2pc|=(ht_arg->prepare==0);
  if (thd->transaction.xid_state.xid.is_null())
    thd->transaction.xid_state.xid.set(thd->query_id);
  DBUG_VOID_RETURN;
}

int ha_prepare(THD *thd)
{
  int error=0, all=1;
  THD_TRANS *trans=all ? &thd->transaction.all : &thd->transaction.stmt;
  Ha_trx_info *ha_info= trans->ha_list;
  DBUG_ENTER("ha_prepare");

  if (ha_info)
  {
    for (; ha_info; ha_info= ha_info->next())
    {
      int err;
      handlerton *ht= ha_info->ht();
      status_var_increment(thd->status_var.ha_prepare_count);
      if (ht->prepare)
      {
        if ((err= ht->prepare(ht, thd, all)))
        {
          my_error(ER_ERROR_DURING_COMMIT, MYF(0), err);
          ha_rollback_trans(thd, all);
          error=1;
          break;
        }
      }
      else
      {
        push_warning_printf(thd, Sql_condition::WARN_LEVEL_WARN,
                            ER_ILLEGAL_HA, ER(ER_ILLEGAL_HA),
                            ha_resolve_storage_engine_name(ht));
      }
    }
  }

  DBUG_RETURN(error);
}

static
uint
ha_check_and_coalesce_trx_read_only(THD *thd, Ha_trx_info *ha_list,
                                    bool all)
{
  /* The number of storage engines that have actual changes. */
  unsigned rw_ha_count= 0;
  Ha_trx_info *ha_info;

  for (ha_info= ha_list; ha_info; ha_info= ha_info->next())
  {
    if (ha_info->is_trx_read_write())
      ++rw_ha_count;

    if (! all)
    {
      Ha_trx_info *ha_info_all= &thd->ha_data[ha_info->ht()->slot].ha_info[1];
      DBUG_ASSERT(ha_info != ha_info_all);
      /*
        Merge read-only/read-write information about statement
        transaction to its enclosing normal transaction. Do this
        only if in a real transaction -- that is, if we know
        that ha_info_all is registered in thd->transaction.all.
        Since otherwise we only clutter the normal transaction flags.
      */
      if (ha_info_all->is_started()) /* FALSE if autocommit. */
        ha_info_all->coalesce_trx_with(ha_info);
    }
    else if (rw_ha_count > 1)
    {
      /*
        It is a normal transaction, so we don't need to merge read/write
        information up, and the need for two-phase commit has been
        already established. Break the loop prematurely.
      */
      break;
    }
  }
  return rw_ha_count;
}


int ha_commit_trans(THD *thd, bool all, bool ignore_global_read_lock)
{
  int error= 0;
  /*
    'all' means that this is either an explicit commit issued by
    user, or an implicit commit issued by a DDL.
  */
  THD_TRANS *trans= all ? &thd->transaction.all : &thd->transaction.stmt;
  /*
    "real" is a nick name for a transaction for which a commit will
    make persistent changes. E.g. a 'stmt' transaction inside a 'all'
    transation is not 'real': even though it's possible to commit it,
    the changes are not durable as they might be rolled back if the
    enclosing 'all' transaction is rolled back.
  */
  bool is_real_trans= all || thd->transaction.all.ha_list == 0;
  Ha_trx_info *ha_info= trans->ha_list;
  DBUG_ENTER("ha_commit_trans");

  DBUG_PRINT("info", ("all=%d thd->in_sub_stmt=%d ha_info=%p is_real_trans=%d",
                      all, thd->in_sub_stmt, ha_info, is_real_trans));
  /*
    We must not commit the normal transaction if a statement
    transaction is pending. Otherwise statement transaction
    flags will not get propagated to its normal transaction's
    counterpart.
  */
  DBUG_ASSERT(thd->transaction.stmt.ha_list == NULL ||
              trans == &thd->transaction.stmt);

  if (thd->in_sub_stmt)
  {
    DBUG_ASSERT(0);
    /*
      Since we don't support nested statement transactions in 5.0,
      we can't commit or rollback stmt transactions while we are inside
      stored functions or triggers. So we simply do nothing now.
      TODO: This should be fixed in later ( >= 5.1) releases.
    */
    if (!all)
      DBUG_RETURN(0);
    /*
      We assume that all statements which commit or rollback main transaction
      are prohibited inside of stored functions or triggers. So they should
      bail out with error even before ha_commit_trans() call. To be 100% safe
      let us throw error in non-debug builds.
    */
    my_error(ER_COMMIT_NOT_ALLOWED_IN_SF_OR_TRG, MYF(0));
    DBUG_RETURN(2);
  }

  MDL_request mdl_request;
  bool release_mdl= false;

  if (ha_info)
  {
    uint rw_ha_count;
    bool rw_trans;

    DBUG_EXECUTE_IF("crash_commit_before", DBUG_SUICIDE(););

    /* Close all cursors that can not survive COMMIT */
    if (is_real_trans)                          /* not a statement commit */
      thd->stmt_map.close_transient_cursors();

    rw_ha_count= ha_check_and_coalesce_trx_read_only(thd, ha_info, all);
    trans->rw_ha_count= rw_ha_count;
    /* rw_trans is TRUE when we in a transaction changing data */
    rw_trans= is_real_trans && (rw_ha_count > 0);

    if (rw_trans && !ignore_global_read_lock)
    {
      /*
        Acquire a metadata lock which will ensure that COMMIT is blocked
        by an active FLUSH TABLES WITH READ LOCK (and vice versa:
        COMMIT in progress blocks FTWRL).

        We allow the owner of FTWRL to COMMIT; we assume that it knows
        what it does.
      */
      mdl_request.init(MDL_key::COMMIT, "", "", MDL_INTENTION_EXCLUSIVE,
                       MDL_EXPLICIT);

      DBUG_PRINT("debug", ("Acquire MDL commit lock"));
      if (thd->mdl_context.acquire_lock(&mdl_request,
                                        thd->variables.lock_wait_timeout))
      {
        ha_rollback_trans(thd, all);
        DBUG_RETURN(1);
      }
      release_mdl= true;

      DEBUG_SYNC(thd, "ha_commit_trans_after_acquire_commit_lock");
    }

    if (rw_trans &&
        opt_readonly &&
        !(thd->security_ctx->master_access & SUPER_ACL) &&
        !thd->slave_thread)
    {
      my_error(ER_OPTION_PREVENTS_STATEMENT, MYF(0), "--read-only");
      ha_rollback_trans(thd, all);
      error= 1;
      goto end;
    }

    if (!trans->no_2pc && (rw_ha_count > 1))
      error= tc_log->prepare(thd, all);
  }
  if (error || (error= tc_log->commit(thd, all)))
  {
    ha_rollback_trans(thd, all);
    error= 1;
    goto end;
  }
  DBUG_EXECUTE_IF("crash_commit_after", DBUG_SUICIDE(););
end:
  if (release_mdl && mdl_request.ticket)
  {
    /*
      We do not always immediately release transactional locks
      after ha_commit_trans() (see uses of ha_enable_transaction()),
      thus we release the commit blocker lock as soon as it's
      not needed.
    */
    DBUG_PRINT("debug", ("Releasing MDL commit lock"));
    thd->mdl_context.release_lock(mdl_request.ticket);
  }
  /* Free resources and perform other cleanup even for 'empty' transactions. */
  if (is_real_trans)
    thd->transaction.cleanup();
  DBUG_RETURN(error);
}

int ha_commit_low(THD *thd, bool all, bool run_after_commit)
{
  int error=0;
  THD_TRANS *trans=all ? &thd->transaction.all : &thd->transaction.stmt;
  Ha_trx_info *ha_info= trans->ha_list, *ha_info_next;
  DBUG_ENTER("ha_commit_low");

  if (ha_info)
  {
    for (; ha_info; ha_info= ha_info_next)
    {
      int err;
      handlerton *ht= ha_info->ht();
      if ((err= ht->commit(ht, thd, all)))
      {
        my_error(ER_ERROR_DURING_COMMIT, MYF(0), err);
        error=1;
      }
      status_var_increment(thd->status_var.ha_commit_count);
      ha_info_next= ha_info->next();
      ha_info->reset(); /* keep it conveniently zero-filled */
    }
    trans->ha_list= 0;
    trans->no_2pc=0;
    trans->rw_ha_count= 0;
    if (all)
    {
#ifdef HAVE_QUERY_CACHE
      if (thd->transaction.changed_tables)
        query_cache.invalidate(thd->transaction.changed_tables);
#endif
    }
  }
  /* Free resources and perform other cleanup even for 'empty' transactions. */
  if (all)
    thd->transaction.cleanup();
  /*
    When the transaction has been committed, we clear the commit_low
    flag. This allow other parts of the system to check if commit_low
    was called.
  */
  thd->transaction.flags.commit_low= false;
  if (run_after_commit)
  {
    /* If commit succeeded, we call the after_commit hook */
    if (!error)
      (void) RUN_HOOK(transaction, after_commit, (thd, all));
    thd->transaction.flags.run_hooks= false;
  }
  DBUG_RETURN(error);
}


int ha_rollback_low(THD *thd, bool all)
{
  THD_TRANS *trans=all ? &thd->transaction.all : &thd->transaction.stmt;
  Ha_trx_info *ha_info= trans->ha_list, *ha_info_next;
  int error= 0;

  if (ha_info)
  {
    /* Close all cursors that can not survive ROLLBACK */
    if (all)                          /* not a statement commit */
      thd->stmt_map.close_transient_cursors();

    for (; ha_info; ha_info= ha_info_next)
    {
      int err;
      handlerton *ht= ha_info->ht();
      if ((err= ht->rollback(ht, thd, all)))
      { // cannot happen
        my_error(ER_ERROR_DURING_ROLLBACK, MYF(0), err);
        error= 1;
      }
      status_var_increment(thd->status_var.ha_rollback_count);
      ha_info_next= ha_info->next();
      ha_info->reset(); /* keep it conveniently zero-filled */
    }
    trans->ha_list= 0;
    trans->no_2pc=0;
    trans->rw_ha_count= 0;
  }

  /*
    Thanks to possibility of MDL deadlock rollback request can come even if
    transaction hasn't been started in any transactional storage engine.
  */
  if (all && thd->transaction_rollback_request &&
      thd->transaction.xid_state.xa_state != XA_NOTR)
    thd->transaction.xid_state.rm_error= thd->get_stmt_da()->sql_errno();

  (void) RUN_HOOK(transaction, after_rollback, (thd, all));
  return error;
}


int ha_rollback_trans(THD *thd, bool all)
{
  int error=0;
#ifndef DBUG_OFF
  THD_TRANS *trans=all ? &thd->transaction.all : &thd->transaction.stmt;
#endif
  /*
    "real" is a nick name for a transaction for which a commit will
    make persistent changes. E.g. a 'stmt' transaction inside a 'all'
    transaction is not 'real': even though it's possible to commit it,
    the changes are not durable as they might be rolled back if the
    enclosing 'all' transaction is rolled back.
    We establish the value of 'is_real_trans' by checking
    if it's an explicit COMMIT or BEGIN statement, or implicit
    commit issued by DDL (in these cases all == TRUE),
    or if we're running in autocommit mode (it's only in the autocommit mode
    ha_commit_one_phase() is called with an empty
    transaction.all.ha_list, see why in trans_register_ha()).
  */
  bool is_real_trans= all || thd->transaction.all.ha_list == NULL;
  DBUG_ENTER("ha_rollback_trans");

  /*
    We must not rollback the normal transaction if a statement
    transaction is pending.
  */
  DBUG_ASSERT(thd->transaction.stmt.ha_list == NULL ||
              trans == &thd->transaction.stmt);

  if (thd->in_sub_stmt)
  {
    DBUG_ASSERT(0);
    /*
      If we are inside stored function or trigger we should not commit or
      rollback current statement transaction. See comment in ha_commit_trans()
      call for more information.
    */
    if (!all)
      DBUG_RETURN(0);
    my_error(ER_COMMIT_NOT_ALLOWED_IN_SF_OR_TRG, MYF(0));
    DBUG_RETURN(1);
  }

  if (tc_log)
    tc_log->rollback(thd, all);

  /* Always cleanup. Even if nht==0. There may be savepoints. */
  if (is_real_trans)
    thd->transaction.cleanup();
  if (all)
    thd->transaction_rollback_request= FALSE;

  /*
    Only call gtid_rollback(THD*), which will purge thd->owned_gtid, if
    complete transaction is being rollback or autocommit=1.
  */
  if (is_real_trans)
    gtid_rollback(thd);

  /*
    If the transaction cannot be rolled back safely, warn; don't warn if this
    is a slave thread (because when a slave thread executes a ROLLBACK, it has
    been read from the binary log, so it's 100% sure and normal to produce
    error ER_WARNING_NOT_COMPLETE_ROLLBACK. If we sent the warning to the
    slave SQL thread, it would not stop the thread but just be printed in
    the error log; but we don't want users to wonder why they have this
    message in the error log, so we don't send it.
  */
#ifndef DBUG_OFF
  thd->transaction.stmt.dbug_unsafe_rollback_flags("stmt");
  thd->transaction.all.dbug_unsafe_rollback_flags("all");
#endif
  if (is_real_trans && thd->transaction.all.cannot_safely_rollback() &&
      !thd->slave_thread && thd->killed != THD::KILL_CONNECTION)
    thd->transaction.push_unsafe_rollback_warnings(thd);
  DBUG_RETURN(error);
}


struct xahton_st {
  XID *xid;
  int result;
};

static my_bool xacommit_handlerton(THD *unused1, plugin_ref plugin,
                                   void *arg)
{
  handlerton *hton= plugin_data(plugin, handlerton *);
  if (hton->state == SHOW_OPTION_YES && hton->recover)
  {
    hton->commit_by_xid(hton, ((struct xahton_st *)arg)->xid);
    ((struct xahton_st *)arg)->result= 0;
  }
  return FALSE;
}

static my_bool xarollback_handlerton(THD *unused1, plugin_ref plugin,
                                     void *arg)
{
  handlerton *hton= plugin_data(plugin, handlerton *);
  if (hton->state == SHOW_OPTION_YES && hton->recover)
  {
    hton->rollback_by_xid(hton, ((struct xahton_st *)arg)->xid);
    ((struct xahton_st *)arg)->result= 0;
  }
  return FALSE;
}


int ha_commit_or_rollback_by_xid(THD *thd, XID *xid, bool commit)
{
  struct xahton_st xaop;
  xaop.xid= xid;
  xaop.result= 1;

  plugin_foreach(NULL, commit ? xacommit_handlerton : xarollback_handlerton,
                 MYSQL_STORAGE_ENGINE_PLUGIN, &xaop);

  gtid_rollback(thd);

  return xaop.result;
}


#ifndef DBUG_OFF

static char* xid_to_str(char *buf, XID *xid)
{
  int i;
  char *s=buf;
  *s++='\'';
  for (i=0; i < xid->gtrid_length+xid->bqual_length; i++)
  {
    uchar c=(uchar)xid->data[i];
    /* is_next_dig is set if next character is a number */
    bool is_next_dig= FALSE;
    if (i < XIDDATASIZE)
    {
      char ch= xid->data[i+1];
      is_next_dig= (ch >= '0' && ch <='9');
    }
    if (i == xid->gtrid_length)
    {
      *s++='\'';
      if (xid->bqual_length)
      {
        *s++='.';
        *s++='\'';
      }
    }
    if (c < 32 || c > 126)
    {
      *s++='\\';
      /*
        If next character is a number, write current character with
        3 octal numbers to ensure that the next number is not seen
        as part of the octal number
      */
      if (c > 077 || is_next_dig)
        *s++=_dig_vec_lower[c >> 6];
      if (c > 007 || is_next_dig)
        *s++=_dig_vec_lower[(c >> 3) & 7];
      *s++=_dig_vec_lower[c & 7];
    }
    else
    {
      if (c == '\'' || c == '\\')
        *s++='\\';
      *s++=c;
    }
  }
  *s++='\'';
  *s=0;
  return buf;
}
#endif

struct xarecover_st
{
  int len, found_foreign_xids, found_my_xids;
  XID *list;
  HASH *commit_list;
  bool dry_run;
};

static my_bool xarecover_handlerton(THD *unused, plugin_ref plugin,
                                    void *arg)
{
  handlerton *hton= plugin_data(plugin, handlerton *);
  struct xarecover_st *info= (struct xarecover_st *) arg;
  int got;

  if (hton->state == SHOW_OPTION_YES && hton->recover)
  {
    while ((got= hton->recover(hton, info->list, info->len)) > 0 )
    {
      sql_print_information("Found %d prepared transaction(s) in %s",
                            got, ha_resolve_storage_engine_name(hton));
      for (int i=0; i < got; i ++)
      {
        my_xid x=info->list[i].get_my_xid();
        if (!x) // not "mine" - that is generated by external TM
        {
#ifndef DBUG_OFF
          char buf[XIDDATASIZE*4+6]; // see xid_to_str
          sql_print_information("ignore xid %s", xid_to_str(buf, info->list+i));
#endif
          xid_cache_insert(info->list+i, XA_PREPARED);
          info->found_foreign_xids++;
          continue;
        }
        if (info->dry_run)
        {
          info->found_my_xids++;
          continue;
        }
        // recovery mode
        if (info->commit_list ?
            my_hash_search(info->commit_list, (uchar *)&x, sizeof(x)) != 0 :
            tc_heuristic_recover == TC_HEURISTIC_RECOVER_COMMIT)
        {
#ifndef DBUG_OFF
          char buf[XIDDATASIZE*4+6]; // see xid_to_str
          sql_print_information("commit xid %s", xid_to_str(buf, info->list+i));
#endif
          hton->commit_by_xid(hton, info->list+i);
        }
        else
        {
#ifndef DBUG_OFF
          char buf[XIDDATASIZE*4+6]; // see xid_to_str
          sql_print_information("rollback xid %s",
                                xid_to_str(buf, info->list+i));
#endif
          hton->rollback_by_xid(hton, info->list+i);
        }
      }
      if (got < info->len)
        break;
    }
  }
  return FALSE;
}

int ha_recover(HASH *commit_list)
{
  struct xarecover_st info;
  DBUG_ENTER("ha_recover");
  info.found_foreign_xids= info.found_my_xids= 0;
  info.commit_list= commit_list;
  info.dry_run= (info.commit_list==0 && tc_heuristic_recover==0);
  info.list= NULL;

  /* commit_list and tc_heuristic_recover cannot be set both */
  DBUG_ASSERT(info.commit_list==0 || tc_heuristic_recover==0);
  /* if either is set, total_ha_2pc must be set too */
  DBUG_ASSERT(info.dry_run || total_ha_2pc>(ulong)opt_bin_log);

  if (total_ha_2pc <= (ulong)opt_bin_log)
    DBUG_RETURN(0);

  if (info.commit_list)
    sql_print_information("Starting crash recovery...");

#ifndef WILL_BE_DELETED_LATER
  /*
    for now, only InnoDB supports 2pc. It means we can always safely
    rollback all pending transactions, without risking inconsistent data
  */
  DBUG_ASSERT(total_ha_2pc == (ulong) opt_bin_log+1); // only InnoDB and binlog
  tc_heuristic_recover= TC_HEURISTIC_RECOVER_ROLLBACK; // forcing ROLLBACK
  info.dry_run=FALSE;
#endif

  for (info.len= MAX_XID_LIST_SIZE ; 
       info.list==0 && info.len > MIN_XID_LIST_SIZE; info.len/=2)
  {
    info.list=(XID *)my_malloc(info.len*sizeof(XID), MYF(0));
  }
  if (!info.list)
  {
    sql_print_error(ER(ER_OUTOFMEMORY),
                    static_cast<int>(info.len*sizeof(XID)));
    DBUG_RETURN(1);
  }

  plugin_foreach(NULL, xarecover_handlerton, 
                 MYSQL_STORAGE_ENGINE_PLUGIN, &info);

  my_free(info.list);
  if (info.found_foreign_xids)
    sql_print_warning("Found %d prepared XA transactions", 
                      info.found_foreign_xids);
  if (info.dry_run && info.found_my_xids)
  {
    sql_print_error("Found %d prepared transactions! It means that mysqld was "
                    "not shut down properly last time and critical recovery "
                    "information (last binlog or %s file) was manually deleted "
                    "after a crash. You have to start mysqld with "
                    "--tc-heuristic-recover switch to commit or rollback "
                    "pending transactions.",
                    info.found_my_xids, opt_tc_log_file);
    DBUG_RETURN(1);
  }
  if (info.commit_list)
    sql_print_information("Crash recovery finished.");
  DBUG_RETURN(0);
}

bool mysql_xa_recover(THD *thd)
{
  List<Item> field_list;
  Protocol *protocol= thd->protocol;
  int i=0;
  XID_STATE *xs;
  DBUG_ENTER("mysql_xa_recover");

  field_list.push_back(new Item_int(NAME_STRING("formatID"), 0, MY_INT32_NUM_DECIMAL_DIGITS));
  field_list.push_back(new Item_int(NAME_STRING("gtrid_length"), 0, MY_INT32_NUM_DECIMAL_DIGITS));
  field_list.push_back(new Item_int(NAME_STRING("bqual_length"), 0, MY_INT32_NUM_DECIMAL_DIGITS));
  field_list.push_back(new Item_empty_string("data",XIDDATASIZE));

  if (protocol->send_result_set_metadata(&field_list,
                            Protocol::SEND_NUM_ROWS | Protocol::SEND_EOF))
    DBUG_RETURN(1);

  mysql_mutex_lock(&LOCK_xid_cache);
  while ((xs= (XID_STATE*) my_hash_element(&xid_cache, i++)))
  {
    if (xs->xa_state==XA_PREPARED)
    {
      protocol->prepare_for_resend();
      protocol->store_longlong((longlong)xs->xid.formatID, FALSE);
      protocol->store_longlong((longlong)xs->xid.gtrid_length, FALSE);
      protocol->store_longlong((longlong)xs->xid.bqual_length, FALSE);
      protocol->store(xs->xid.data, xs->xid.gtrid_length+xs->xid.bqual_length,
                      &my_charset_bin);
      if (protocol->write())
      {
        mysql_mutex_unlock(&LOCK_xid_cache);
        DBUG_RETURN(1);
      }
    }
  }

  mysql_mutex_unlock(&LOCK_xid_cache);
  my_eof(thd);
  DBUG_RETURN(0);
}

int ha_release_temporary_latches(THD *thd)
{
  Ha_trx_info *info;

  /*
    Note that below we assume that only transactional storage engines
    may need release_temporary_latches(). If this will ever become false,
    we could iterate on thd->open_tables instead (and remove duplicates
    as if (!seen[hton->slot]) { seen[hton->slot]=1; ... }).
  */
  for (info= thd->transaction.stmt.ha_list; info; info= info->next())
  {
    handlerton *hton= info->ht();
    if (hton && hton->release_temporary_latches)
        hton->release_temporary_latches(hton, thd);
  }
  return 0;
}

int ha_rollback_to_savepoint(THD *thd, SAVEPOINT *sv)
{
  int error=0;
  THD_TRANS *trans= (thd->in_sub_stmt ? &thd->transaction.stmt :
                                        &thd->transaction.all);
  Ha_trx_info *ha_info, *ha_info_next;

  DBUG_ENTER("ha_rollback_to_savepoint");

  trans->no_2pc=0;
  trans->rw_ha_count= 0;
  /*
    rolling back to savepoint in all storage engines that were part of the
    transaction when the savepoint was set
  */
  for (ha_info= sv->ha_list; ha_info; ha_info= ha_info->next())
  {
    int err;
    handlerton *ht= ha_info->ht();
    DBUG_ASSERT(ht);
    DBUG_ASSERT(ht->savepoint_set != 0);
    if ((err= ht->savepoint_rollback(ht, thd,
                                     (uchar *)(sv+1)+ht->savepoint_offset)))
    { // cannot happen
      my_error(ER_ERROR_DURING_ROLLBACK, MYF(0), err);
      error=1;
    }
    status_var_increment(thd->status_var.ha_savepoint_rollback_count);
    trans->no_2pc|= ht->prepare == 0;
  }
  /*
    rolling back the transaction in all storage engines that were not part of
    the transaction when the savepoint was set
  */
  for (ha_info= trans->ha_list; ha_info != sv->ha_list;
       ha_info= ha_info_next)
  {
    int err;
    handlerton *ht= ha_info->ht();
    if ((err= ht->rollback(ht, thd, !thd->in_sub_stmt)))
    { // cannot happen
      my_error(ER_ERROR_DURING_ROLLBACK, MYF(0), err);
      error=1;
    }
    status_var_increment(thd->status_var.ha_rollback_count);
    ha_info_next= ha_info->next();
    ha_info->reset(); /* keep it conveniently zero-filled */
  }
  trans->ha_list= sv->ha_list;
  DBUG_RETURN(error);
}

int ha_prepare_low(THD *thd, bool all)
{
  int error= 0;
  THD_TRANS *trans=all ? &thd->transaction.all : &thd->transaction.stmt;
  Ha_trx_info *ha_info= trans->ha_list;
  DBUG_ENTER("ha_prepare_low");

  if (ha_info)
  {
    for (; ha_info && !error; ha_info= ha_info->next())
    {
      int err= 0;
      handlerton *ht= ha_info->ht();
      /*
        Do not call two-phase commit if this particular
        transaction is read-only. This allows for simpler
        implementation in engines that are always read-only.
      */
      if (!ha_info->is_trx_read_write())
        continue;
      if ((err= ht->prepare(ht, thd, all)))
      {
        my_error(ER_ERROR_DURING_COMMIT, MYF(0), err);
        error= 1;
      }
      status_var_increment(thd->status_var.ha_prepare_count);
    }
    DBUG_EXECUTE_IF("crash_commit_after_prepare", DBUG_SUICIDE(););
  }

  DBUG_RETURN(error);
}

int ha_savepoint(THD *thd, SAVEPOINT *sv)
{
  int error=0;
  THD_TRANS *trans= (thd->in_sub_stmt ? &thd->transaction.stmt :
                                        &thd->transaction.all);
  Ha_trx_info *ha_info= trans->ha_list;
  DBUG_ENTER("ha_savepoint");

  for (; ha_info; ha_info= ha_info->next())
  {
    int err;
    handlerton *ht= ha_info->ht();
    DBUG_ASSERT(ht);
    if (! ht->savepoint_set)
    {
      my_error(ER_CHECK_NOT_IMPLEMENTED, MYF(0), "SAVEPOINT");
      error=1;
      break;
    }
    if ((err= ht->savepoint_set(ht, thd, (uchar *)(sv+1)+ht->savepoint_offset)))
    { // cannot happen
      my_error(ER_GET_ERRNO, MYF(0), err);
      error=1;
    }
    status_var_increment(thd->status_var.ha_savepoint_count);
  }
  /*
    Remember the list of registered storage engines. All new
    engines are prepended to the beginning of the list.
  */
  sv->ha_list= trans->ha_list;

  DBUG_RETURN(error);
}

int ha_release_savepoint(THD *thd, SAVEPOINT *sv)
{
  int error=0;
  Ha_trx_info *ha_info= sv->ha_list;
  DBUG_ENTER("ha_release_savepoint");

  for (; ha_info; ha_info= ha_info->next())
  {
    int err;
    handlerton *ht= ha_info->ht();
    /* Savepoint life time is enclosed into transaction life time. */
    DBUG_ASSERT(ht);
    if (!ht->savepoint_release)
      continue;
    if ((err= ht->savepoint_release(ht, thd,
                                    (uchar *)(sv+1) + ht->savepoint_offset)))
    { // cannot happen
      my_error(ER_GET_ERRNO, MYF(0), err);
      error=1;
    }
  }
  DBUG_RETURN(error);
}


static my_bool snapshot_handlerton(THD *thd, plugin_ref plugin,
                                   void *arg)
{
  handlerton *hton= plugin_data(plugin, handlerton *);
  if (hton->state == SHOW_OPTION_YES &&
      hton->start_consistent_snapshot)
  {
    hton->start_consistent_snapshot(hton, thd);
    *((bool *)arg)= false;
  }
  return FALSE;
}

int ha_start_consistent_snapshot(THD *thd)
{
  bool warn= true;

  plugin_foreach(thd, snapshot_handlerton, MYSQL_STORAGE_ENGINE_PLUGIN, &warn);

  /*
    Same idea as when one wants to CREATE TABLE in one engine which does not
    exist:
  */
  if (warn)
    push_warning(thd, Sql_condition::WARN_LEVEL_WARN, ER_UNKNOWN_ERROR,
                 "This MySQL server does not support any "
                 "consistent-read capable storage engine");
  return 0;
}


static my_bool flush_handlerton(THD *thd, plugin_ref plugin,
                                void *arg)
{
  handlerton *hton= plugin_data(plugin, handlerton *);
  if (hton->state == SHOW_OPTION_YES && hton->flush_logs && 
      hton->flush_logs(hton))
    return TRUE;
  return FALSE;
}


bool ha_flush_logs(handlerton *db_type)
{
  if (db_type == NULL)
  {
    if (plugin_foreach(NULL, flush_handlerton,
                          MYSQL_STORAGE_ENGINE_PLUGIN, 0))
      return TRUE;
  }
  else
  {
    if (db_type->state != SHOW_OPTION_YES ||
        (db_type->flush_logs && db_type->flush_logs(db_type)))
      return TRUE;
  }
  return FALSE;
}


const char *get_canonical_filename(handler *file, const char *path,
                                   char *tmp_path)
{
  uint i;
  if (lower_case_table_names != 2 || (file->ha_table_flags() & HA_FILE_BASED))
    return path;

  for (i= 0; i <= mysql_tmpdir_list.max; i++)
  {
    if (is_prefix(path, mysql_tmpdir_list.list[i]))
      return path;
  }

  /* Ensure that table handler get path in lower case */
  if (tmp_path != path)
    strmov(tmp_path, path);

  /*
    we only should turn into lowercase database/table part
    so start the process after homedirectory
  */
  my_casedn_str(files_charset_info, tmp_path + mysql_data_home_len);
  return tmp_path;
}


struct Ha_delete_table_error_handler: public Internal_error_handler
{
public:
  virtual bool handle_condition(THD *thd,
                                uint sql_errno,
                                const char* sqlstate,
                                Sql_condition::enum_warning_level level,
                                const char* msg,
                                Sql_condition ** cond_hdl);
  char buff[MYSQL_ERRMSG_SIZE];
};


bool
Ha_delete_table_error_handler::
handle_condition(THD *,
                 uint,
                 const char*,
                 Sql_condition::enum_warning_level,
                 const char* msg,
                 Sql_condition ** cond_hdl)
{
  *cond_hdl= NULL;
  /* Grab the error message */
  strmake(buff, msg, sizeof(buff)-1);
  return TRUE;
}


int ha_delete_table(THD *thd, handlerton *table_type, const char *path,
                    const char *db, const char *alias, bool generate_warning)
{
  handler *file;
  char tmp_path[FN_REFLEN];
  int error;
  TABLE dummy_table;
  TABLE_SHARE dummy_share;
  DBUG_ENTER("ha_delete_table");

  memset(&dummy_table, 0, sizeof(dummy_table));
  memset(&dummy_share, 0, sizeof(dummy_share));
  dummy_table.s= &dummy_share;

  /* DB_TYPE_UNKNOWN is used in ALTER TABLE when renaming only .frm files */
  if (table_type == NULL ||
      ! (file=get_new_handler((TABLE_SHARE*)0, thd->mem_root, table_type)))
    DBUG_RETURN(ENOENT);

  path= get_canonical_filename(file, path, tmp_path);
  if ((error= file->ha_delete_table(path)) && generate_warning)
  {
    /*
      Because file->print_error() use my_error() to generate the error message
      we use an internal error handler to intercept it and store the text
      in a temporary buffer. Later the message will be presented to user
      as a warning.
    */
    Ha_delete_table_error_handler ha_delete_table_error_handler;

    /* Fill up strucutures that print_error may need */
    dummy_share.path.str= (char*) path;
    dummy_share.path.length= strlen(path);
    dummy_share.db.str= (char*) db;
    dummy_share.db.length= strlen(db);
    dummy_share.table_name.str= (char*) alias;
    dummy_share.table_name.length= strlen(alias);
    dummy_table.alias= alias;

    file->change_table_ptr(&dummy_table, &dummy_share);

    thd->push_internal_handler(&ha_delete_table_error_handler);
    file->print_error(error, 0);

    thd->pop_internal_handler();

    /*
      XXX: should we convert *all* errors to warnings here?
      What if the error is fatal?
    */
    push_warning(thd, Sql_condition::WARN_LEVEL_WARN, error,
                ha_delete_table_error_handler.buff);
  }
  delete file;

#ifdef HAVE_PSI_TABLE_INTERFACE
  if (likely(error == 0))
  {
    my_bool temp_table= (my_bool)is_prefix(alias, tmp_file_prefix);
    PSI_TABLE_CALL(drop_table_share)
      (temp_table, db, strlen(db), alias, strlen(alias));
  }
#endif

  DBUG_RETURN(error);
}

/****************************************************************************
** General handler functions
****************************************************************************/
handler *handler::clone(const char *name, MEM_ROOT *mem_root)
{
  handler *new_handler= get_new_handler(table->s, mem_root, ht);

  if (!new_handler)
    return NULL;
  if (new_handler->set_ha_share_ref(ha_share))
    goto err;

  /*
    Allocate 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(ref_length)*2)))
    goto err;
  /*
    TODO: Implement a more efficient way to have more than one index open for
    the same table instance. The ha_open call is not cachable for clone.
  */
  if (new_handler->ha_open(table, name, table->db_stat,
                           HA_OPEN_IGNORE_IF_LOCKED))
    goto err;

  return new_handler;

err:
  delete new_handler;
  return NULL;
}



void handler::ha_statistic_increment(ulonglong SSV::*offset) const
{
  status_var_increment(table->in_use->status_var.*offset);
}

void **handler::ha_data(THD *thd) const
{
  return thd_ha_data(thd, ht);
}

THD *handler::ha_thd(void) const
{
  DBUG_ASSERT(!table || !table->in_use || table->in_use == current_thd);
  return (table && table->in_use) ? table->in_use : current_thd;
}

void handler::unbind_psi()
{
#ifdef HAVE_PSI_TABLE_INTERFACE
  DBUG_ASSERT(m_lock_type == F_UNLCK);
  DBUG_ASSERT(inited == NONE);
  /*
    Notify the instrumentation that this table is not owned
    by this thread any more.
  */
  PSI_TABLE_CALL(unbind_table)(m_psi);
#endif
}

void handler::rebind_psi()
{
#ifdef HAVE_PSI_TABLE_INTERFACE
  DBUG_ASSERT(m_lock_type == F_UNLCK);
  DBUG_ASSERT(inited == NONE);
  /*
    Notify the instrumentation that this table is now owned
    by this thread.
  */
  PSI_table_share *share_psi= ha_table_share_psi(table_share);
  m_psi= PSI_TABLE_CALL(rebind_table)(share_psi, this, m_psi);
#endif
}

PSI_table_share *handler::ha_table_share_psi(const TABLE_SHARE *share) const
{
  return share->m_psi;
}

int handler::ha_open(TABLE *table_arg, const char *name, int mode,
                     int test_if_locked)
{
  int error;
  DBUG_ENTER("handler::ha_open");
  DBUG_PRINT("enter",
             ("name: %s  db_type: %d  db_stat: %d  mode: %d  lock_test: %d",
              name, ht->db_type, table_arg->db_stat, mode,
              test_if_locked));

  table= table_arg;
  DBUG_ASSERT(table->s == table_share);
  DBUG_ASSERT(m_lock_type == F_UNLCK);
  DBUG_PRINT("info", ("old m_lock_type: %d F_UNLCK %d", m_lock_type, F_UNLCK));
  DBUG_ASSERT(alloc_root_inited(&table->mem_root));

  if ((error=open(name,mode,test_if_locked)))
  {
    if ((error == EACCES || error == EROFS) && mode == O_RDWR &&
        (table->db_stat & HA_TRY_READ_ONLY))
    {
      table->db_stat|=HA_READ_ONLY;
      error=open(name,O_RDONLY,test_if_locked);
    }
  }
  if (error)
  {
    my_errno= error;                            /* Safeguard */
    DBUG_PRINT("error",("error: %d  errno: %d",error,errno));
  }
  else
  {
    DBUG_ASSERT(m_psi == NULL);
    DBUG_ASSERT(table_share != NULL);
#ifdef HAVE_PSI_TABLE_INTERFACE
    /*
      Do not call this for partitions handlers, since it may take too much
      resources.
      So only use the m_psi on table level, not for individual partitions.
    */
    if (!(test_if_locked & HA_OPEN_NO_PSI_CALL))
    {
      PSI_table_share *share_psi= ha_table_share_psi(table_share);
      m_psi= PSI_TABLE_CALL(open_table)(share_psi, this);
    }
#endif

    if (table->s->db_options_in_use & HA_OPTION_READ_ONLY_DATA)
      table->db_stat|=HA_READ_ONLY;
    (void) extra(HA_EXTRA_NO_READCHECK);        // Not needed in SQL

    /* ref is already allocated for us if we're called from handler::clone() */
    if (!ref && !(ref= (uchar*) alloc_root(&table->mem_root, 
                                          ALIGN_SIZE(ref_length)*2)))
    {
      ha_close();
      error=HA_ERR_OUT_OF_MEM;
    }
    else
      dup_ref=ref+ALIGN_SIZE(ref_length);
    cached_table_flags= table_flags();
  }
  DBUG_RETURN(error);
}


int handler::ha_close(void)
{
  DBUG_ENTER("handler::ha_close");
#ifdef HAVE_PSI_TABLE_INTERFACE
  PSI_TABLE_CALL(close_table)(m_psi);
  m_psi= NULL; /* instrumentation handle, invalid after close_table() */
#endif
  // TODO: set table= NULL to mark the handler as closed?
  DBUG_ASSERT(m_psi == NULL);
  DBUG_ASSERT(m_lock_type == F_UNLCK);
  DBUG_ASSERT(inited == NONE);
  DBUG_RETURN(close());
}


int handler::ha_index_init(uint idx, bool sorted)
{
  DBUG_EXECUTE_IF("ha_index_init_fail", return HA_ERR_TABLE_DEF_CHANGED;);
  int result;
  DBUG_ENTER("ha_index_init");
  DBUG_ASSERT(table_share->tmp_table != NO_TMP_TABLE ||
              m_lock_type != F_UNLCK);
  DBUG_ASSERT(inited == NONE);
  if (!(result= index_init(idx, sorted)))
    inited= INDEX;
  end_range= NULL;
  DBUG_RETURN(result);
}


int handler::ha_index_end()
{
  DBUG_ENTER("ha_index_end");
  /* SQL HANDLER function can call this without having it locked. */
  DBUG_ASSERT(table->open_by_handler ||
              table_share->tmp_table != NO_TMP_TABLE ||
              m_lock_type != F_UNLCK);
  DBUG_ASSERT(inited == INDEX);
  inited= NONE;
  end_range= NULL;
  DBUG_RETURN(index_end());
}


int handler::ha_rnd_init(bool scan)
{
  DBUG_EXECUTE_IF("ha_rnd_init_fail", return HA_ERR_TABLE_DEF_CHANGED;);
  int result;
  DBUG_ENTER("ha_rnd_init");
  DBUG_ASSERT(table_share->tmp_table != NO_TMP_TABLE ||
              m_lock_type != F_UNLCK);
  DBUG_ASSERT(inited == NONE || (inited == RND && scan));
  inited= (result= rnd_init(scan)) ? NONE : RND;
  end_range= NULL;
  DBUG_RETURN(result);
}


int handler::ha_rnd_end()
{
  DBUG_ENTER("ha_rnd_end");
  /* SQL HANDLER function can call this without having it locked. */
  DBUG_ASSERT(table->open_by_handler ||
              table_share->tmp_table != NO_TMP_TABLE ||
              m_lock_type != F_UNLCK);
  DBUG_ASSERT(inited == RND);
  inited= NONE;
  end_range= NULL;
  DBUG_RETURN(rnd_end());
}


int handler::ha_rnd_next(uchar *buf)
{
  int result;
  DBUG_ENTER("handler::ha_rnd_next");
  DBUG_ASSERT(table_share->tmp_table != NO_TMP_TABLE ||
              m_lock_type != F_UNLCK);
  DBUG_ASSERT(inited == RND);

  MYSQL_TABLE_IO_WAIT(m_psi, PSI_TABLE_FETCH_ROW, MAX_KEY, 0,
    { result= rnd_next(buf); })
  DBUG_RETURN(result);
}


int handler::ha_rnd_pos(uchar *buf, uchar *pos)
{
  int result;
  DBUG_ENTER("handler::ha_rnd_pos");
  DBUG_ASSERT(table_share->tmp_table != NO_TMP_TABLE ||
              m_lock_type != F_UNLCK);
  /* TODO: Find out how to solve ha_rnd_pos when finding duplicate update. */
  /* DBUG_ASSERT(inited == RND); */

  MYSQL_TABLE_IO_WAIT(m_psi, PSI_TABLE_FETCH_ROW, MAX_KEY, 0,
    { result= rnd_pos(buf, pos); })
  DBUG_RETURN(result);
}


int handler::ha_index_read_map(uchar *buf, const uchar *key,
                               key_part_map keypart_map,
                               enum ha_rkey_function find_flag)
{
  int result;
  DBUG_ENTER("handler::ha_index_read_map");
  DBUG_ASSERT(table_share->tmp_table != NO_TMP_TABLE ||
              m_lock_type != F_UNLCK);
  DBUG_ASSERT(inited == INDEX);

  MYSQL_TABLE_IO_WAIT(m_psi, PSI_TABLE_FETCH_ROW, active_index, 0,
    { result= index_read_map(buf, key, keypart_map, find_flag); })
  DBUG_RETURN(result);
}

int handler::ha_index_read_last_map(uchar *buf, const uchar *key,
                                    key_part_map keypart_map)
{
  int result;
  DBUG_ENTER("handler::ha_index_read_last_map");
  DBUG_ASSERT(table_share->tmp_table != NO_TMP_TABLE ||
              m_lock_type != F_UNLCK);
  DBUG_ASSERT(inited == INDEX);

  MYSQL_TABLE_IO_WAIT(m_psi, PSI_TABLE_FETCH_ROW, active_index, 0,
    { result= index_read_last_map(buf, key, keypart_map); })
  DBUG_RETURN(result);
}


int handler::ha_index_read_idx_map(uchar *buf, uint index, const uchar *key,
                                   key_part_map keypart_map,
                                   enum ha_rkey_function find_flag)
{
  int result;
  DBUG_ASSERT(table_share->tmp_table != NO_TMP_TABLE ||
              m_lock_type != F_UNLCK);
  DBUG_ASSERT(end_range == NULL);

  MYSQL_TABLE_IO_WAIT(m_psi, PSI_TABLE_FETCH_ROW, index, 0,
    { result= index_read_idx_map(buf, index, key, keypart_map, find_flag); })
  return result;
}


int handler::ha_index_next(uchar * buf)
{
  int result;
  DBUG_ENTER("handler::ha_index_next");
  DBUG_ASSERT(table_share->tmp_table != NO_TMP_TABLE ||
              m_lock_type != F_UNLCK);
  DBUG_ASSERT(inited == INDEX);

  MYSQL_TABLE_IO_WAIT(m_psi, PSI_TABLE_FETCH_ROW, active_index, 0,
    { result= index_next(buf); })
  DBUG_RETURN(result);
}


int handler::ha_index_prev(uchar * buf)
{
  int result;
  DBUG_ENTER("handler::ha_index_prev");
  DBUG_ASSERT(table_share->tmp_table != NO_TMP_TABLE ||
              m_lock_type != F_UNLCK);
  DBUG_ASSERT(inited == INDEX);

  MYSQL_TABLE_IO_WAIT(m_psi, PSI_TABLE_FETCH_ROW, active_index, 0,
    { result= index_prev(buf); })
  DBUG_RETURN(result);
}


int handler::ha_index_first(uchar * buf)
{
  int result;
  DBUG_ASSERT(table_share->tmp_table != NO_TMP_TABLE ||
              m_lock_type != F_UNLCK);
  DBUG_ASSERT(inited == INDEX);

  MYSQL_TABLE_IO_WAIT(m_psi, PSI_TABLE_FETCH_ROW, active_index, 0,
    { result= index_first(buf); })
  return result;
}


int handler::ha_index_last(uchar * buf)
{
  int result;
  DBUG_ASSERT(table_share->tmp_table != NO_TMP_TABLE ||
              m_lock_type != F_UNLCK);
  DBUG_ASSERT(inited == INDEX);

  MYSQL_TABLE_IO_WAIT(m_psi, PSI_TABLE_FETCH_ROW, active_index, 0,
    { result= index_last(buf); })
  return result;
}


int handler::ha_index_next_same(uchar *buf, const uchar *key, uint keylen)
{
  int result;
  DBUG_ASSERT(table_share->tmp_table != NO_TMP_TABLE ||
              m_lock_type != F_UNLCK);
  DBUG_ASSERT(inited == INDEX);

  MYSQL_TABLE_IO_WAIT(m_psi, PSI_TABLE_FETCH_ROW, active_index, 0,
    { result= index_next_same(buf, key, keylen); })
  return result;
}


int handler::ha_index_read(uchar *buf, const uchar *key, uint key_len,
                           enum ha_rkey_function find_flag)
{
  int result;
  DBUG_ASSERT(table_share->tmp_table != NO_TMP_TABLE ||
              m_lock_type != F_UNLCK);
  DBUG_ASSERT(inited == INDEX);

  MYSQL_TABLE_IO_WAIT(m_psi, PSI_TABLE_FETCH_ROW, active_index, 0,
    { result= index_read(buf, key, key_len, find_flag); })
  return result;
}


int handler::ha_index_read_last(uchar *buf, const uchar *key, uint key_len)
{
  int result;
  DBUG_ASSERT(table_share->tmp_table != NO_TMP_TABLE ||
              m_lock_type != F_UNLCK);
  DBUG_ASSERT(inited == INDEX);

  MYSQL_TABLE_IO_WAIT(m_psi, PSI_TABLE_FETCH_ROW, active_index, 0,
    { result= index_read_last(buf, key, key_len); })
  return result;
}


int handler::read_first_row(uchar * buf, uint primary_key)
{
  register int error;
  DBUG_ENTER("handler::read_first_row");

  ha_statistic_increment(&SSV::ha_read_first_count);

  /*
    If there is very few deleted rows in the table, find the first row by
    scanning the table.
    TODO remove the test for HA_READ_ORDER
  */
  if (stats.deleted < 10 || primary_key >= MAX_KEY ||
      !(index_flags(primary_key, 0, 0) & HA_READ_ORDER))
  {
    if (!(error= ha_rnd_init(1)))
    {
      while ((error= rnd_next(buf)) == HA_ERR_RECORD_DELETED)
        /* skip deleted row */;
      const int end_error= ha_rnd_end();
      if (!error)
        error= end_error;
    }
  }
  else
  {
    /* Find the first row through the primary key */
    if (!(error= ha_index_init(primary_key, 0)))
    {
      error= ha_index_first(buf);
      const int end_error= ha_index_end();
      if (!error)
        error= end_error;
    }
  }
  DBUG_RETURN(error);
}

inline ulonglong
compute_next_insert_id(ulonglong nr,struct system_variables *variables)
{
  const ulonglong save_nr= nr;

  if (variables->auto_increment_increment == 1)
    nr= nr + 1; // optimization of the formula below
  else
  {
    nr= (((nr+ variables->auto_increment_increment -
           variables->auto_increment_offset)) /
         (ulonglong) variables->auto_increment_increment);
    nr= (nr* (ulonglong) variables->auto_increment_increment +
         variables->auto_increment_offset);
  }

  if (unlikely(nr <= save_nr))
    return ULONGLONG_MAX;

  return nr;
}


void handler::adjust_next_insert_id_after_explicit_value(ulonglong nr)
{
  /*
    If we have set THD::next_insert_id previously and plan to insert an
    explicitely-specified value larger than this, we need to increase
    THD::next_insert_id to be greater than the explicit value.
  */
  if ((next_insert_id > 0) && (nr >= next_insert_id))
    set_next_insert_id(compute_next_insert_id(nr, &table->in_use->variables));
}


inline ulonglong
prev_insert_id(ulonglong nr, struct system_variables *variables)
{
  if (unlikely(nr < variables->auto_increment_offset))
  {
    /*
      There's nothing good we can do here. That is a pathological case, where
      the offset is larger than the column's max possible value, i.e. not even
      the first sequence value may be inserted. User will receive warning.
    */
    DBUG_PRINT("info",("auto_increment: nr: %lu cannot honour "
                       "auto_increment_offset: %lu",
                       (ulong) nr, variables->auto_increment_offset));
    return nr;
  }
  if (variables->auto_increment_increment == 1)
    return nr; // optimization of the formula below
  nr= (((nr - variables->auto_increment_offset)) /
       (ulonglong) variables->auto_increment_increment);
  return (nr * (ulonglong) variables->auto_increment_increment +
          variables->auto_increment_offset);
}


#define AUTO_INC_DEFAULT_NB_ROWS 1 // Some prefer 1024 here
#define AUTO_INC_DEFAULT_NB_MAX_BITS 16
#define AUTO_INC_DEFAULT_NB_MAX ((1 << AUTO_INC_DEFAULT_NB_MAX_BITS) - 1)

int handler::update_auto_increment()
{
  ulonglong nr, nb_reserved_values;
  bool append= FALSE;
  THD *thd= table->in_use;
  struct system_variables *variables= &thd->variables;
  DBUG_ASSERT(table_share->tmp_table != NO_TMP_TABLE ||
              m_lock_type != F_UNLCK);
  DBUG_ENTER("handler::update_auto_increment");

  /*
    next_insert_id is a "cursor" into the reserved interval, it may go greater
    than the interval, but not smaller.
  */
  DBUG_ASSERT(next_insert_id >= auto_inc_interval_for_cur_row.minimum());

  if ((nr= table->next_number_field->val_int()) != 0 ||
      (table->auto_increment_field_not_null &&
      thd->variables.sql_mode & MODE_NO_AUTO_VALUE_ON_ZERO))
  {
    /*
      Update next_insert_id if we had already generated a value in this
      statement (case of INSERT VALUES(null),(3763),(null):
      the last NULL needs to insert 3764, not the value of the first NULL plus
      1).
    */
    adjust_next_insert_id_after_explicit_value(nr);
    insert_id_for_cur_row= 0; // didn't generate anything
    DBUG_RETURN(0);
  }

  if ((nr= next_insert_id) >= auto_inc_interval_for_cur_row.maximum())
  {
    /* next_insert_id is beyond what is reserved, so we reserve more. */
    const Discrete_interval *forced=
      thd->auto_inc_intervals_forced.get_next();
    if (forced != NULL)
    {
      nr= forced->minimum();
      nb_reserved_values= forced->values();
    }
    else
    {
      /*
        handler::estimation_rows_to_insert was set by
        handler::ha_start_bulk_insert(); if 0 it means "unknown".
      */
      ulonglong nb_desired_values;
      /*
        If an estimation was given to the engine:
        - use it.
        - if we already reserved numbers, it means the estimation was
        not accurate, then we'll reserve 2*AUTO_INC_DEFAULT_NB_ROWS the 2nd
        time, twice that the 3rd time etc.
        If no estimation was given, use those increasing defaults from the
        start, starting from AUTO_INC_DEFAULT_NB_ROWS.
        Don't go beyond a max to not reserve "way too much" (because
        reservation means potentially losing unused values).
        Note that in prelocked mode no estimation is given.
      */

      if ((auto_inc_intervals_count == 0) && (estimation_rows_to_insert > 0))
        nb_desired_values= estimation_rows_to_insert;
      else if ((auto_inc_intervals_count == 0) &&
               (thd->lex->many_values.elements > 0))
      {
        /*
          For multi-row inserts, if the bulk inserts cannot be started, the
          handler::estimation_rows_to_insert will not be set. But we still
          want to reserve the autoinc values.
        */
        nb_desired_values= thd->lex->many_values.elements;
      }
      else /* go with the increasing defaults */
      {
        /* avoid overflow in formula, with this if() */
        if (auto_inc_intervals_count <= AUTO_INC_DEFAULT_NB_MAX_BITS)
        {
          nb_desired_values= AUTO_INC_DEFAULT_NB_ROWS *
            (1 << auto_inc_intervals_count);
          set_if_smaller(nb_desired_values, AUTO_INC_DEFAULT_NB_MAX);
        }
        else
          nb_desired_values= AUTO_INC_DEFAULT_NB_MAX;
      }
      /* This call ignores all its parameters but nr, currently */
      get_auto_increment(variables->auto_increment_offset,
                         variables->auto_increment_increment,
                         nb_desired_values, &nr,
                         &nb_reserved_values);
      if (nr == ULONGLONG_MAX)
        DBUG_RETURN(HA_ERR_AUTOINC_READ_FAILED);  // Mark failure

      /*
        That rounding below should not be needed when all engines actually
        respect offset and increment in get_auto_increment(). But they don't
        so we still do it. Wonder if for the not-first-in-index we should do
        it. Hope that this rounding didn't push us out of the interval; even
        if it did we cannot do anything about it (calling the engine again
        will not help as we inserted no row).
      */
      nr= compute_next_insert_id(nr-1, variables);
    }

    if (table->s->next_number_keypart == 0)
    {
      /* We must defer the appending until "nr" has been possibly truncated */
      append= TRUE;
    }
    else
    {
      /*
        For such auto_increment there is no notion of interval, just a
        singleton. The interval is not even stored in
        thd->auto_inc_interval_for_cur_row, so we are sure to call the engine
        for next row.
      */
      DBUG_PRINT("info",("auto_increment: special not-first-in-index"));
    }
  }

  if (unlikely(nr == ULONGLONG_MAX))
      DBUG_RETURN(HA_ERR_AUTOINC_ERANGE); 

  DBUG_PRINT("info",("auto_increment: %lu", (ulong) nr));

  if (unlikely(table->next_number_field->store((longlong) nr, TRUE)))
  {
    /*
      first test if the query was aborted due to strict mode constraints
    */
    if (thd->killed == THD::KILL_BAD_DATA)
      DBUG_RETURN(HA_ERR_AUTOINC_ERANGE);

    /*
      field refused this value (overflow) and truncated it, use the result of
      the truncation (which is going to be inserted); however we try to
      decrease it to honour auto_increment_* variables.
      That will shift the left bound of the reserved interval, we don't
      bother shifting the right bound (anyway any other value from this
      interval will cause a duplicate key).
    */
    nr= prev_insert_id(table->next_number_field->val_int(), variables);
    if (unlikely(table->next_number_field->store((longlong) nr, TRUE)))
      nr= table->next_number_field->val_int();
  }
  if (append)
  {
    auto_inc_interval_for_cur_row.replace(nr, nb_reserved_values,
                                          variables->auto_increment_increment);
    auto_inc_intervals_count++;
    /* Row-based replication does not need to store intervals in binlog */
    if (mysql_bin_log.is_open() && !thd->is_current_stmt_binlog_format_row())
        thd->auto_inc_intervals_in_cur_stmt_for_binlog.append(auto_inc_interval_for_cur_row.minimum(),
                                                              auto_inc_interval_for_cur_row.values(),
                                                              variables->auto_increment_increment);
  }

  /*
    Record this autogenerated value. If the caller then
    succeeds to insert this value, it will call
    record_first_successful_insert_id_in_cur_stmt()
    which will set first_successful_insert_id_in_cur_stmt if it's not
    already set.
  */
  insert_id_for_cur_row= nr;
  /*
    Set next insert id to point to next auto-increment value to be able to
    handle multi-row statements.
  */
  set_next_insert_id(compute_next_insert_id(nr, variables));

  DBUG_RETURN(0);
}


void handler::column_bitmaps_signal()
{
  DBUG_ENTER("column_bitmaps_signal");
  DBUG_PRINT("info", ("read_set: 0x%lx  write_set: 0x%lx", (long) table->read_set,
                      (long)table->write_set));
  DBUG_VOID_RETURN;
}


void handler::get_auto_increment(ulonglong offset, ulonglong increment,
                                 ulonglong nb_desired_values,
                                 ulonglong *first_value,
                                 ulonglong *nb_reserved_values)
{
  ulonglong nr;
  int error;
  DBUG_ENTER("handler::get_auto_increment");

  (void) extra(HA_EXTRA_KEYREAD);
  table->mark_columns_used_by_index_no_reset(table->s->next_number_index,
                                        table->read_set);
  column_bitmaps_signal();

  if (ha_index_init(table->s->next_number_index, 1))
  {
    /* This should never happen, assert in debug, and fail in release build */
    DBUG_ASSERT(0);
    *first_value= ULONGLONG_MAX;
    DBUG_VOID_RETURN;
  }

  if (table->s->next_number_keypart == 0)
  {                                             // Autoincrement at key-start
    error= ha_index_last(table->record[1]);
    /*
      MySQL implicitely assumes such method does locking (as MySQL decides to
      use nr+increment without checking again with the handler, in
      handler::update_auto_increment()), so reserves to infinite.
    */
    *nb_reserved_values= ULONGLONG_MAX;
  }
  else
  {
    uchar key[MAX_KEY_LENGTH];
    key_copy(key, table->record[0],
             table->key_info + table->s->next_number_index,
             table->s->next_number_key_offset);
    error= ha_index_read_map(table->record[1], key,
                             make_prev_keypart_map(table->s->next_number_keypart),
                             HA_READ_PREFIX_LAST);
    /*
      MySQL needs to call us for next row: assume we are inserting ("a",null)
      here, we return 3, and next this statement will want to insert
      ("b",null): there is no reason why ("b",3+1) would be the good row to
      insert: maybe it already exists, maybe 3+1 is too large...
    */
    *nb_reserved_values= 1;
  }

  if (error)
  {
    if (error == HA_ERR_END_OF_FILE || error == HA_ERR_KEY_NOT_FOUND)
    {
      /* No entry found, start with 1. */
      nr= 1;
    }
    else
    {
      DBUG_ASSERT(0);
      nr= ULONGLONG_MAX;
    }
  }
  else
    nr= ((ulonglong) table->next_number_field->
         val_int_offset(table->s->rec_buff_length)+1);
  ha_index_end();
  (void) extra(HA_EXTRA_NO_KEYREAD);
  *first_value= nr;
  DBUG_VOID_RETURN;
}


void handler::ha_release_auto_increment()
{
  DBUG_ASSERT(table_share->tmp_table != NO_TMP_TABLE ||
              m_lock_type != F_UNLCK ||
              (!next_insert_id && !insert_id_for_cur_row));
  release_auto_increment();
  insert_id_for_cur_row= 0;
  auto_inc_interval_for_cur_row.replace(0, 0, 0);
  auto_inc_intervals_count= 0;
  if (next_insert_id > 0)
  {
    next_insert_id= 0;
    /*
      this statement used forced auto_increment values if there were some,
      wipe them away for other statements.
    */
    table->in_use->auto_inc_intervals_forced.empty();
  }
}


void print_keydup_error(TABLE *table, KEY *key, const char *msg, myf errflag)
{
  /* Write the duplicated key in the error message */
  char key_buff[MAX_KEY_LENGTH];
  String str(key_buff,sizeof(key_buff),system_charset_info);

  if (key == NULL)
  {
    /* Key is unknown */
    str.copy("", 0, system_charset_info);
    my_printf_error(ER_DUP_ENTRY, msg, errflag, str.c_ptr(), "*UNKNOWN*");
  }
  else
  {
    /* Table is opened and defined at this point */
    key_unpack(&str,table, key);
    uint max_length=MYSQL_ERRMSG_SIZE-(uint) strlen(msg);
    if (str.length() >= max_length)
    {
      str.length(max_length-4);
      str.append(STRING_WITH_LEN("..."));
    }
    my_printf_error(ER_DUP_ENTRY, msg, errflag, str.c_ptr_safe(), key->name);
  }
}


void print_keydup_error(TABLE *table, KEY *key, myf errflag)
{
  print_keydup_error(table, key, ER(ER_DUP_ENTRY_WITH_KEY_NAME), errflag);
}


void handler::print_error(int error, myf errflag)
{
  DBUG_ENTER("handler::print_error");
  DBUG_PRINT("enter",("error: %d",error));

  int textno=ER_GET_ERRNO;
  switch (error) {
  case EACCES:
    textno=ER_OPEN_AS_READONLY;
    break;
  case EAGAIN:
    textno=ER_FILE_USED;
    break;
  case ENOENT:
    {
      char errbuf[MYSYS_STRERROR_SIZE];
      textno=ER_FILE_NOT_FOUND;
      my_error(textno, errflag, table_share->table_name.str,
               error, my_strerror(errbuf, sizeof(errbuf), error));
    }
    break;
  case HA_ERR_KEY_NOT_FOUND:
  case HA_ERR_NO_ACTIVE_RECORD:
  case HA_ERR_RECORD_DELETED:
  case HA_ERR_END_OF_FILE:
    textno=ER_KEY_NOT_FOUND;
    break;
  case HA_ERR_WRONG_MRG_TABLE_DEF:
    textno=ER_WRONG_MRG_TABLE;
    break;
  case HA_ERR_FOUND_DUPP_KEY:
  {
    uint key_nr= table ? get_dup_key(error) : -1;
    if ((int) key_nr >= 0)
    {
      print_keydup_error(table,
                         key_nr == MAX_KEY ? NULL : &table->key_info[key_nr],
                         errflag);
      DBUG_VOID_RETURN;
    }
    textno=ER_DUP_KEY;
    break;
  }
  case HA_ERR_FOREIGN_DUPLICATE_KEY:
  {
    DBUG_ASSERT(table_share->tmp_table != NO_TMP_TABLE ||
                m_lock_type != F_UNLCK);

    char rec_buf[MAX_KEY_LENGTH];
    String rec(rec_buf, sizeof(rec_buf), system_charset_info);
    /* Table is opened and defined at this point */

    /*
      Just print the subset of fields that are part of the first index,
      printing the whole row from there is not easy.
    */
    key_unpack(&rec, table, &table->key_info[0]);

    char child_table_name[NAME_LEN + 1];
    char child_key_name[NAME_LEN + 1];
    if (get_foreign_dup_key(child_table_name, sizeof(child_table_name),
                            child_key_name, sizeof(child_key_name)))
    {
      my_error(ER_FOREIGN_DUPLICATE_KEY_WITH_CHILD_INFO, errflag,
               table_share->table_name.str, rec.c_ptr_safe(),
               child_table_name, child_key_name);
    }
    else
    {
      my_error(ER_FOREIGN_DUPLICATE_KEY_WITHOUT_CHILD_INFO, errflag,
               table_share->table_name.str, rec.c_ptr_safe());
    }
    DBUG_VOID_RETURN;
  }
  case HA_ERR_NULL_IN_SPATIAL:
    my_error(ER_CANT_CREATE_GEOMETRY_OBJECT, errflag);
    DBUG_VOID_RETURN;
  case HA_ERR_FOUND_DUPP_UNIQUE:
    textno=ER_DUP_UNIQUE;
    break;
  case HA_ERR_RECORD_CHANGED:
    textno=ER_CHECKREAD;
    break;
  case HA_ERR_CRASHED:
    textno=ER_NOT_KEYFILE;
    break;
  case HA_ERR_WRONG_IN_RECORD:
    textno= ER_CRASHED_ON_USAGE;
    break;
  case HA_ERR_CRASHED_ON_USAGE:
    textno=ER_CRASHED_ON_USAGE;
    break;
  case HA_ERR_NOT_A_TABLE:
    textno= error;
    break;
  case HA_ERR_CRASHED_ON_REPAIR:
    textno=ER_CRASHED_ON_REPAIR;
    break;
  case HA_ERR_OUT_OF_MEM:
    textno=ER_OUT_OF_RESOURCES;
    break;
  case HA_ERR_WRONG_COMMAND:
    textno=ER_ILLEGAL_HA;
    break;
  case HA_ERR_OLD_FILE:
    textno=ER_OLD_KEYFILE;
    break;
  case HA_ERR_UNSUPPORTED:
    textno=ER_UNSUPPORTED_EXTENSION;
    break;
  case HA_ERR_RECORD_FILE_FULL:
  case HA_ERR_INDEX_FILE_FULL:
  {
    textno=ER_RECORD_FILE_FULL;
    /* Write the error message to error log */
    errflag|= ME_NOREFRESH;
    break;
  }
  case HA_ERR_LOCK_WAIT_TIMEOUT:
    textno=ER_LOCK_WAIT_TIMEOUT;
    break;
  case HA_ERR_LOCK_TABLE_FULL:
    textno=ER_LOCK_TABLE_FULL;
    break;
  case HA_ERR_LOCK_DEADLOCK:
    textno=ER_LOCK_DEADLOCK;
    break;
  case HA_ERR_READ_ONLY_TRANSACTION:
    textno=ER_READ_ONLY_TRANSACTION;
    break;
  case HA_ERR_CANNOT_ADD_FOREIGN:
    textno=ER_CANNOT_ADD_FOREIGN;
    break;
  case HA_ERR_ROW_IS_REFERENCED:
  {
    String str;
    get_error_message(error, &str);
    my_error(ER_ROW_IS_REFERENCED_2, errflag, str.c_ptr_safe());
    DBUG_VOID_RETURN;
  }
  case HA_ERR_NO_REFERENCED_ROW:
  {
    String str;
    get_error_message(error, &str);
    my_error(ER_NO_REFERENCED_ROW_2, errflag, str.c_ptr_safe());
    DBUG_VOID_RETURN;
  }
  case HA_ERR_TABLE_DEF_CHANGED:
    textno=ER_TABLE_DEF_CHANGED;
    break;
  case HA_ERR_NO_SUCH_TABLE:
    my_error(ER_NO_SUCH_TABLE, errflag, table_share->db.str,
             table_share->table_name.str);
    DBUG_VOID_RETURN;
  case HA_ERR_RBR_LOGGING_FAILED:
    textno= ER_BINLOG_ROW_LOGGING_FAILED;
    break;
  case HA_ERR_DROP_INDEX_FK:
  {
    const char *ptr= "???";
    uint key_nr= table ? get_dup_key(error) : -1;
    if ((int) key_nr >= 0)
      ptr= table->key_info[key_nr].name;
    my_error(ER_DROP_INDEX_FK, errflag, ptr);
    DBUG_VOID_RETURN;
  }
  case HA_ERR_TABLE_NEEDS_UPGRADE:
    textno=ER_TABLE_NEEDS_UPGRADE;
    break;
  case HA_ERR_NO_PARTITION_FOUND:
    textno=ER_WRONG_PARTITION_NAME;
    break;
  case HA_ERR_TABLE_READONLY:
    textno= ER_OPEN_AS_READONLY;
    break;
  case HA_ERR_AUTOINC_READ_FAILED:
    textno= ER_AUTOINC_READ_FAILED;
    break;
  case HA_ERR_AUTOINC_ERANGE:
    textno= ER_WARN_DATA_OUT_OF_RANGE;
    break;
  case HA_ERR_TOO_MANY_CONCURRENT_TRXS:
    textno= ER_TOO_MANY_CONCURRENT_TRXS;
    break;
  case HA_ERR_INDEX_COL_TOO_LONG:
    textno= ER_INDEX_COLUMN_TOO_LONG;
    break;
  case HA_ERR_NOT_IN_LOCK_PARTITIONS:
    textno=ER_ROW_DOES_NOT_MATCH_GIVEN_PARTITION_SET;
    break;
  case HA_ERR_INDEX_CORRUPT:
    textno= ER_INDEX_CORRUPT;
    break;
  case HA_ERR_UNDO_REC_TOO_BIG:
    textno= ER_UNDO_RECORD_TOO_BIG;
    break;
  case HA_ERR_TABLE_IN_FK_CHECK:
    textno= ER_TABLE_IN_FK_CHECK;
    break;
  case HA_WRONG_CREATE_OPTION:
    textno= ER_ILLEGAL_HA;
    break;
  case HA_ERR_TOO_MANY_FIELDS:
    textno= ER_TOO_MANY_FIELDS;
    break;
  case HA_ERR_INNODB_READ_ONLY:
    textno= ER_INNODB_READ_ONLY;
    break;
  default:
    {
      /* The error was "unknown" to this function.
         Ask handler if it has got a message for this error */
      bool temporary= FALSE;
      String str;
      temporary= get_error_message(error, &str);
      if (!str.is_empty())
      {
        const char* engine= table_type();
        if (temporary)
          my_error(ER_GET_TEMPORARY_ERRMSG, errflag, error, str.ptr(), engine);
        else
          my_error(ER_GET_ERRMSG, errflag, error, str.ptr(), engine);
      }
      else
        my_error(ER_GET_ERRNO,errflag,error);
      DBUG_VOID_RETURN;
    }
  }
  if (textno != ER_FILE_NOT_FOUND)
    my_error(textno, errflag, table_share->table_name.str, error);
  DBUG_VOID_RETURN;
}


bool handler::get_error_message(int error, String* buf)
{
  return FALSE;
}


int handler::check_collation_compatibility()
{
  ulong mysql_version= table->s->mysql_version;

  if (mysql_version < 50124)
  {
    KEY *key= table->key_info;
    KEY *key_end= key + table->s->keys;
    for (; key < key_end; key++)
    {
      KEY_PART_INFO *key_part= key->key_part;
      KEY_PART_INFO *key_part_end= key_part + key->user_defined_key_parts;
      for (; key_part < key_part_end; key_part++)
      {
        if (!key_part->fieldnr)
          continue;
        Field *field= table->field[key_part->fieldnr - 1];
        uint cs_number= field->charset()->number;
        if ((mysql_version < 50048 &&
             (cs_number == 11 || /* ascii_general_ci - bug #29499, bug #27562 */
              cs_number == 41 || /* latin7_general_ci - bug #29461 */
              cs_number == 42 || /* latin7_general_cs - bug #29461 */
              cs_number == 20 || /* latin7_estonian_cs - bug #29461 */
              cs_number == 21 || /* latin2_hungarian_ci - bug #29461 */
              cs_number == 22 || /* koi8u_general_ci - bug #29461 */
              cs_number == 23 || /* cp1251_ukrainian_ci - bug #29461 */
              cs_number == 26)) || /* cp1250_general_ci - bug #29461 */
             (mysql_version < 50124 &&
             (cs_number == 33 || /* utf8_general_ci - bug #27877 */
              cs_number == 35))) /* ucs2_general_ci - bug #27877 */
          return HA_ADMIN_NEEDS_UPGRADE;
      }  
    }  
  }  
  return 0;
}


int handler::ha_check_for_upgrade(HA_CHECK_OPT *check_opt)
{
  int error;
  KEY *keyinfo, *keyend;
  KEY_PART_INFO *keypart, *keypartend;

  if (!table->s->mysql_version)
  {
    /* check for blob-in-key error */
    keyinfo= table->key_info;
    keyend= table->key_info + table->s->keys;
    for (; keyinfo < keyend; keyinfo++)
    {
      keypart= keyinfo->key_part;
      keypartend= keypart + keyinfo->user_defined_key_parts;
      for (; keypart < keypartend; keypart++)
      {
        if (!keypart->fieldnr)
          continue;
        Field *field= table->field[keypart->fieldnr-1];
        if (field->type() == MYSQL_TYPE_BLOB)
        {
          if (check_opt->sql_flags & TT_FOR_UPGRADE)
            check_opt->flags= T_MEDIUM;
          return HA_ADMIN_NEEDS_CHECK;
        }
      }
    }
  }
  if (table->s->frm_version != FRM_VER_TRUE_VARCHAR)
    return HA_ADMIN_NEEDS_ALTER;

  if ((error= check_collation_compatibility()))
    return error;
    
  return check_for_upgrade(check_opt);
}


int handler::check_old_types()
{
  Field** field;

  for (field= table->field; (*field); field++)
  {
    if (table->s->mysql_version == 0) // prior to MySQL 5.0
    {
      /* check for bad DECIMAL field */
      if ((*field)->type() == MYSQL_TYPE_NEWDECIMAL) // TODO: error? MYSQL_TYPE_DECIMAL?
      {
        return HA_ADMIN_NEEDS_ALTER;
      }
      if ((*field)->type() == MYSQL_TYPE_VAR_STRING)
      {
        return HA_ADMIN_NEEDS_ALTER;
      }
    }
    if ((*field)->type() == MYSQL_TYPE_YEAR && (*field)->field_length == 2)
      return HA_ADMIN_NEEDS_ALTER; // obsolete YEAR(2) type
  }
  return 0;
}


static bool update_frm_version(TABLE *table)
{
  char path[FN_REFLEN];
  File file;
  int result= 1;
  DBUG_ENTER("update_frm_version");

  /*
    No need to update frm version in case table was created or checked
    by server with the same version. This also ensures that we do not
    update frm version for temporary tables as this code doesn't support
    temporary tables.
  */
  if (table->s->mysql_version == MYSQL_VERSION_ID)
    DBUG_RETURN(0);

  strxmov(path, table->s->normalized_path.str, reg_ext, NullS);

  if ((file= mysql_file_open(key_file_frm,
                             path, O_RDWR|O_BINARY, MYF(MY_WME))) >= 0)
  {
    uchar version[4];

    int4store(version, MYSQL_VERSION_ID);

    if ((result= mysql_file_pwrite(file, (uchar*) version, 4, 51L, MYF_RW)))
      goto err;

    table->s->mysql_version= MYSQL_VERSION_ID;
  }
err:
  if (file >= 0)
    (void) mysql_file_close(file, MYF(MY_WME));
  DBUG_RETURN(result);
}



uint handler::get_dup_key(int error)
{
  DBUG_ASSERT(table_share->tmp_table != NO_TMP_TABLE ||
              m_lock_type != F_UNLCK);
  DBUG_ENTER("handler::get_dup_key");
  table->file->errkey  = (uint) -1;
  if (error == HA_ERR_FOUND_DUPP_KEY ||
      error == HA_ERR_FOUND_DUPP_UNIQUE || error == HA_ERR_NULL_IN_SPATIAL ||
      error == HA_ERR_DROP_INDEX_FK)
    table->file->info(HA_STATUS_ERRKEY | HA_STATUS_NO_LOCK);
  DBUG_RETURN(table->file->errkey);
}


int handler::delete_table(const char *name)
{
  int saved_error= 0;
  int error= 0;
  int enoent_or_zero= ENOENT;                   // Error if no file was deleted
  char buff[FN_REFLEN];
  DBUG_ASSERT(m_lock_type == F_UNLCK);

  for (const char **ext=bas_ext(); *ext ; ext++)
  {
    fn_format(buff, name, "", *ext, MY_UNPACK_FILENAME|MY_APPEND_EXT);
    if (mysql_file_delete_with_symlink(key_file_misc, buff, MYF(0)))
    {
      if (my_errno != ENOENT)
      {
        /*
          If error on the first existing file, return the error.
          Otherwise delete as much as possible.
        */
        if (enoent_or_zero)
          return my_errno;
        saved_error= my_errno;
      }
    }
    else
      enoent_or_zero= 0;                        // No error for ENOENT
    error= enoent_or_zero;
  }
  return saved_error ? saved_error : error;
}


int handler::rename_table(const char * from, const char * to)
{
  int error= 0;
  const char **ext, **start_ext;
  start_ext= bas_ext();
  for (ext= start_ext; *ext ; ext++)
  {
    if (rename_file_ext(from, to, *ext))
    {
      if ((error=my_errno) != ENOENT)
        break;
      error= 0;
    }
  }
  if (error)
  {
    /* Try to revert the rename. Ignore errors. */
    for (; ext >= start_ext; ext--)
      rename_file_ext(to, from, *ext);
  }
  return error;
}


void handler::drop_table(const char *name)
{
  close();
  delete_table(name);
}


int handler::ha_check(THD *thd, HA_CHECK_OPT *check_opt)
{
  int error;
  DBUG_ASSERT(table_share->tmp_table != NO_TMP_TABLE ||
              m_lock_type != F_UNLCK);

  if ((table->s->mysql_version >= MYSQL_VERSION_ID) &&
      (check_opt->sql_flags & TT_FOR_UPGRADE))
    return 0;

  if (table->s->mysql_version < MYSQL_VERSION_ID)
  {
    if ((error= check_old_types()))
      return error;
    error= ha_check_for_upgrade(check_opt);
    if (error && (error != HA_ADMIN_NEEDS_CHECK))
      return error;
    if (!error && (check_opt->sql_flags & TT_FOR_UPGRADE))
      return 0;
  }
  if ((error= check(thd, check_opt)))
    return error;
  /* Skip updating frm version if not main handler. */
  if (table->file != this)
    return error;
  return update_frm_version(table);
}

inline
void
handler::mark_trx_read_write()
{
  Ha_trx_info *ha_info= &ha_thd()->ha_data[ht->slot].ha_info[0];
  /*
    When a storage engine method is called, the transaction must
    have been started, unless it's a DDL call, for which the
    storage engine starts the transaction internally, and commits
    it internally, without registering in the ha_list.
    Unfortunately here we can't know know for sure if the engine
    has registered the transaction or not, so we must check.
  */
  if (ha_info->is_started())
  {
    DBUG_ASSERT(has_transactions());
    /*
      table_share can be NULL in ha_delete_table(). See implementation
      of standalone function ha_delete_table() in sql_base.cc.
    */
    if (table_share == NULL || table_share->tmp_table == NO_TMP_TABLE)
      ha_info->set_trx_read_write();
  }
}


int handler::ha_repair(THD* thd, HA_CHECK_OPT* check_opt)
{
  int result;
  mark_trx_read_write();

  result= repair(thd, check_opt);
  DBUG_ASSERT(result == HA_ADMIN_NOT_IMPLEMENTED ||
              ha_table_flags() & HA_CAN_REPAIR);

  if (result == HA_ADMIN_OK)
    result= update_frm_version(table);
  return result;
}


void handler::ha_start_bulk_insert(ha_rows rows)
{
  DBUG_ENTER("handler::ha_start_bulk_insert");
  DBUG_ASSERT(table_share->tmp_table != NO_TMP_TABLE ||
              m_lock_type == F_WRLCK);
  estimation_rows_to_insert= rows;
  start_bulk_insert(rows);
  DBUG_VOID_RETURN;
}


int handler::ha_end_bulk_insert()
{
  DBUG_ENTER("handler::ha_end_bulk_insert");
  DBUG_ASSERT(table_share->tmp_table != NO_TMP_TABLE ||
              m_lock_type == F_WRLCK);
  estimation_rows_to_insert= 0;
  DBUG_RETURN(end_bulk_insert());
}


int
handler::ha_bulk_update_row(const uchar *old_data, uchar *new_data,
                            uint *dup_key_found)
{
  DBUG_ASSERT(table_share->tmp_table != NO_TMP_TABLE ||
              m_lock_type == F_WRLCK);
  mark_trx_read_write();

  return bulk_update_row(old_data, new_data, dup_key_found);
}


int
handler::ha_delete_all_rows()
{
  DBUG_ASSERT(table_share->tmp_table != NO_TMP_TABLE ||
              m_lock_type == F_WRLCK);
  mark_trx_read_write();

  return delete_all_rows();
}


int
handler::ha_truncate()
{
  DBUG_ASSERT(table_share->tmp_table != NO_TMP_TABLE ||
              m_lock_type == F_WRLCK);
  mark_trx_read_write();

  return truncate();
}


int
handler::ha_reset_auto_increment(ulonglong value)
{
  DBUG_ASSERT(table_share->tmp_table != NO_TMP_TABLE ||
              m_lock_type == F_WRLCK);
  mark_trx_read_write();

  return reset_auto_increment(value);
}


int
handler::ha_optimize(THD* thd, HA_CHECK_OPT* check_opt)
{
  DBUG_ASSERT(table_share->tmp_table != NO_TMP_TABLE ||
              m_lock_type == F_WRLCK);
  mark_trx_read_write();

  return optimize(thd, check_opt);
}


int
handler::ha_analyze(THD* thd, HA_CHECK_OPT* check_opt)
{
  DBUG_ASSERT(table_share->tmp_table != NO_TMP_TABLE ||
              m_lock_type != F_UNLCK);
  mark_trx_read_write();

  return analyze(thd, check_opt);
}


bool
handler::ha_check_and_repair(THD *thd)
{
  DBUG_ASSERT(table_share->tmp_table != NO_TMP_TABLE ||
              m_lock_type == F_UNLCK);
  mark_trx_read_write();

  return check_and_repair(thd);
}


int
handler::ha_disable_indexes(uint mode)
{
  DBUG_ASSERT(table_share->tmp_table != NO_TMP_TABLE ||
              m_lock_type != F_UNLCK);
  mark_trx_read_write();

  return disable_indexes(mode);
}


int
handler::ha_enable_indexes(uint mode)
{
  DBUG_ASSERT(table_share->tmp_table != NO_TMP_TABLE ||
              m_lock_type != F_UNLCK);
  mark_trx_read_write();

  return enable_indexes(mode);
}


int
handler::ha_discard_or_import_tablespace(my_bool discard)
{
  DBUG_ASSERT(table_share->tmp_table != NO_TMP_TABLE ||
              m_lock_type == F_WRLCK);
  mark_trx_read_write();

  return discard_or_import_tablespace(discard);
}


bool handler::ha_prepare_inplace_alter_table(TABLE *altered_table,
                                             Alter_inplace_info *ha_alter_info)
{
  DBUG_ASSERT(table_share->tmp_table != NO_TMP_TABLE ||
              m_lock_type != F_UNLCK);
  mark_trx_read_write();

  return prepare_inplace_alter_table(altered_table, ha_alter_info);
}


bool handler::ha_commit_inplace_alter_table(TABLE *altered_table,
                                            Alter_inplace_info *ha_alter_info,
                                            bool commit)
{
   /*
     At this point we should have an exclusive metadata lock on the table.
     The exception is if we're about to roll back changes (commit= false).
     In this case, we might be rolling back after a failed lock upgrade,
     so we could be holding the same lock level as for inplace_alter_table().
   */
   DBUG_ASSERT(ha_thd()->mdl_context.is_lock_owner(MDL_key::TABLE,
                                                   table->s->db.str,
                                                   table->s->table_name.str,
                                                   MDL_EXCLUSIVE) ||
               !commit);

   return commit_inplace_alter_table(altered_table, ha_alter_info, commit);
}


/*
   Default implementation to support in-place alter table
   and old online add/drop index API
*/

enum_alter_inplace_result
handler::check_if_supported_inplace_alter(TABLE *altered_table,
                                          Alter_inplace_info *ha_alter_info)
{
  DBUG_ENTER("check_if_supported_alter");

  HA_CREATE_INFO *create_info= ha_alter_info->create_info;

  Alter_inplace_info::HA_ALTER_FLAGS inplace_offline_operations=
    Alter_inplace_info::ALTER_COLUMN_EQUAL_PACK_LENGTH |
    Alter_inplace_info::ALTER_COLUMN_NAME |
    Alter_inplace_info::ALTER_COLUMN_DEFAULT |
    Alter_inplace_info::CHANGE_CREATE_OPTION |
    Alter_inplace_info::ALTER_RENAME;

  /* Is there at least one operation that requires copy algorithm? */
  if (ha_alter_info->handler_flags & ~inplace_offline_operations)
    DBUG_RETURN(HA_ALTER_INPLACE_NOT_SUPPORTED);

  /*
    ALTER TABLE tbl_name CONVERT TO CHARACTER SET .. and
    ALTER TABLE table_name DEFAULT CHARSET = .. most likely
    change column charsets and so not supported in-place through
    old API.

    Changing of PACK_KEYS, MAX_ROWS and ROW_FORMAT options were
    not supported as in-place operations in old API either.
  */
  if (create_info->used_fields & (HA_CREATE_USED_CHARSET |
                                  HA_CREATE_USED_DEFAULT_CHARSET |
                                  HA_CREATE_USED_PACK_KEYS |
                                  HA_CREATE_USED_MAX_ROWS) ||
      (table->s->row_type != create_info->row_type))
    DBUG_RETURN(HA_ALTER_INPLACE_NOT_SUPPORTED);

  uint table_changes= (ha_alter_info->handler_flags &
                       Alter_inplace_info::ALTER_COLUMN_EQUAL_PACK_LENGTH) ?
    IS_EQUAL_PACK_LENGTH : IS_EQUAL_YES;
  if (table->file->check_if_incompatible_data(create_info, table_changes)
      == COMPATIBLE_DATA_YES)
    DBUG_RETURN(HA_ALTER_INPLACE_EXCLUSIVE_LOCK);

  DBUG_RETURN(HA_ALTER_INPLACE_NOT_SUPPORTED);
}


/*
   Default implementation to support in-place alter table
   and old online add/drop index API
*/

void handler::notify_table_changed()
{
  ha_create_handler_files(table->s->path.str, NULL, CHF_INDEX_FLAG, NULL);
}


void Alter_inplace_info::report_unsupported_error(const char *not_supported,
                                                  const char *try_instead)
{
  if (unsupported_reason == NULL)
    my_error(ER_ALTER_OPERATION_NOT_SUPPORTED, MYF(0),
             not_supported, try_instead);
  else
    my_error(ER_ALTER_OPERATION_NOT_SUPPORTED_REASON, MYF(0),
             not_supported, unsupported_reason, try_instead);
}


int
handler::ha_rename_table(const char *from, const char *to)
{
  DBUG_ASSERT(m_lock_type == F_UNLCK);
  mark_trx_read_write();

  return rename_table(from, to);
}


int
handler::ha_delete_table(const char *name)
{
  DBUG_ASSERT(m_lock_type == F_UNLCK);
  mark_trx_read_write();

  return delete_table(name);
}


void
handler::ha_drop_table(const char *name)
{
  DBUG_ASSERT(m_lock_type == F_UNLCK);
  mark_trx_read_write();

  return drop_table(name);
}


int
handler::ha_create(const char *name, TABLE *form, HA_CREATE_INFO *info)
{
  DBUG_ASSERT(m_lock_type == F_UNLCK);
  mark_trx_read_write();

  return create(name, form, info);
}


int
handler::ha_create_handler_files(const char *name, const char *old_name,
                        int action_flag, HA_CREATE_INFO *info)
{
  /*
    Normally this is done when unlocked, but in fast_alter_partition_table,
    it is done on an already locked handler when preparing to alter/rename
    partitions.
  */
  DBUG_ASSERT(m_lock_type == F_UNLCK ||
              (!old_name && strcmp(name, table_share->path.str)));
  mark_trx_read_write();

  return create_handler_files(name, old_name, action_flag, info);
}


int
handler::ha_change_partitions(HA_CREATE_INFO *create_info,
                     const char *path,
                     ulonglong * const copied,
                     ulonglong * const deleted,
                     const uchar *pack_frm_data,
                     size_t pack_frm_len)
{
  /*
    Must have at least RDLCK or be a TMP table. Read lock is needed to read
    from current partitions and write lock will be taken on new partitions.
  */
  DBUG_ASSERT(table_share->tmp_table != NO_TMP_TABLE ||
              m_lock_type != F_UNLCK);
  mark_trx_read_write();

  return change_partitions(create_info, path, copied, deleted,
                           pack_frm_data, pack_frm_len);
}


int
handler::ha_drop_partitions(const char *path)
{
  DBUG_ASSERT(!table->db_stat);

  mark_trx_read_write();

  return drop_partitions(path);
}


int
handler::ha_rename_partitions(const char *path)
{
  DBUG_ASSERT(!table->db_stat);
  mark_trx_read_write();

  return rename_partitions(path);
}


int ha_enable_transaction(THD *thd, bool on)
{
  int error=0;
  DBUG_ENTER("ha_enable_transaction");
  DBUG_PRINT("enter", ("on: %d", (int) on));

  if ((thd->transaction.flags.enabled= on))
  {
    /*
      Now all storage engines should have transaction handling enabled.
      But some may have it enabled all the time - "disabling" transactions
      is an optimization hint that storage engine is free to ignore.
      So, let's commit an open transaction (if any) now.
    */
    if (!(error= ha_commit_trans(thd, 0)))
      error= trans_commit_implicit(thd);
  }
  DBUG_RETURN(error);
}

int handler::index_next_same(uchar *buf, const uchar *key, uint keylen)
{
  int error;
  DBUG_ENTER("index_next_same");
  if (!(error=index_next(buf)))
  {
    my_ptrdiff_t ptrdiff= buf - table->record[0];
    uchar *UNINIT_VAR(save_record_0);
    KEY *UNINIT_VAR(key_info);
    KEY_PART_INFO *UNINIT_VAR(key_part);
    KEY_PART_INFO *UNINIT_VAR(key_part_end);

    /*
      key_cmp_if_same() compares table->record[0] against 'key'.
      In parts it uses table->record[0] directly, in parts it uses
      field objects with their local pointers into table->record[0].
      If 'buf' is distinct from table->record[0], we need to move
      all record references. This is table->record[0] itself and
      the field pointers of the fields used in this key.
    */
    if (ptrdiff)
    {
      save_record_0= table->record[0];
      table->record[0]= buf;
      key_info= table->key_info + active_index;
      key_part= key_info->key_part;
      key_part_end= key_part + key_info->user_defined_key_parts;
      for (; key_part < key_part_end; key_part++)
      {
        DBUG_ASSERT(key_part->field);
        key_part->field->move_field_offset(ptrdiff);
      }
    }

    if (key_cmp_if_same(table, key, active_index, keylen))
    {
      table->status=STATUS_NOT_FOUND;
      error=HA_ERR_END_OF_FILE;
    }

    /* Move back if necessary. */
    if (ptrdiff)
    {
      table->record[0]= save_record_0;
      for (key_part= key_info->key_part; key_part < key_part_end; key_part++)
        key_part->field->move_field_offset(-ptrdiff);
    }
  }
  DBUG_RETURN(error);
}


void handler::get_dynamic_partition_info(PARTITION_STATS *stat_info,
                                         uint part_id)
{
  info(HA_STATUS_CONST | HA_STATUS_TIME | HA_STATUS_VARIABLE |
       HA_STATUS_NO_LOCK);
  stat_info->records=              stats.records;
  stat_info->mean_rec_length=      stats.mean_rec_length;
  stat_info->data_file_length=     stats.data_file_length;
  stat_info->max_data_file_length= stats.max_data_file_length;
  stat_info->index_file_length=    stats.index_file_length;
  stat_info->delete_length=        stats.delete_length;
  stat_info->create_time=          stats.create_time;
  stat_info->update_time=          stats.update_time;
  stat_info->check_time=           stats.check_time;
  stat_info->check_sum=            0;
  if (table_flags() & (ulong) HA_HAS_CHECKSUM)
    stat_info->check_sum= checksum();
  return;
}


/****************************************************************************
** Some general functions that isn't in the handler class
****************************************************************************/

int ha_create_table(THD *thd, const char *path,
                    const char *db, const char *table_name,
                    HA_CREATE_INFO *create_info,
                    bool update_create_info,
                    bool is_temp_table)
{
  int error= 1;
  TABLE table;
  char name_buff[FN_REFLEN];
  const char *name;
  TABLE_SHARE share;
  bool saved_abort_on_warning;
  DBUG_ENTER("ha_create_table");
#ifdef HAVE_PSI_TABLE_INTERFACE
  my_bool temp_table= (my_bool)is_temp_table ||
               (my_bool)is_prefix(table_name, tmp_file_prefix) ||
               (create_info->options & HA_LEX_CREATE_TMP_TABLE ? TRUE : FALSE);
#endif
  
  init_tmp_table_share(thd, &share, db, 0, table_name, path);
  if (open_table_def(thd, &share, 0))
    goto err;

#ifdef HAVE_PSI_TABLE_INTERFACE
  share.m_psi= PSI_TABLE_CALL(get_table_share)(temp_table, &share);
#endif

  if (open_table_from_share(thd, &share, "", 0, (uint) READ_ALL, 0, &table,
                            TRUE))
    goto err;

  if (update_create_info)
    update_create_info_from_table(create_info, &table);

  name= get_canonical_filename(table.file, share.path.str, name_buff);

  saved_abort_on_warning = thd->abort_on_warning; 
  thd->abort_on_warning = false;
  error= table.file->ha_create(name, &table, create_info);
  thd->abort_on_warning = saved_abort_on_warning;
  if (error)
  {
    table.file->print_error(error, MYF(0));
#ifdef HAVE_PSI_TABLE_INTERFACE
    PSI_TABLE_CALL(drop_table_share)
      (temp_table, db, strlen(db), table_name, strlen(table_name));
#endif
  }
  (void) closefrm(&table, 0);
err:
  free_table_share(&share);
  DBUG_RETURN(error != 0);
}

int ha_create_table_from_engine(THD* thd, const char *db, const char *name)
{
  int error;
  uchar *frmblob;
  size_t frmlen;
  char path[FN_REFLEN + 1];
  HA_CREATE_INFO create_info;
  TABLE table;
  TABLE_SHARE share;
  DBUG_ENTER("ha_create_table_from_engine");
  DBUG_PRINT("enter", ("name '%s'.'%s'", db, name));

  memset(&create_info, 0, sizeof(create_info));
  if ((error= ha_discover(thd, db, name, &frmblob, &frmlen)))
  {
    /* Table could not be discovered and thus not created */
    DBUG_RETURN(error);
  }

  /*
    Table exists in handler and could be discovered
    frmblob and frmlen are set, write the frm to disk
  */

  build_table_filename(path, sizeof(path) - 1, db, name, "", 0);
  // Save the frm file
  error= writefrm(path, frmblob, frmlen);
  my_free(frmblob);
  if (error)
    DBUG_RETURN(2);

  init_tmp_table_share(thd, &share, db, 0, name, path);
  if (open_table_def(thd, &share, 0))
  {
    DBUG_RETURN(3);
  }

#ifdef HAVE_PSI_TABLE_INTERFACE
  /*
    Table discovery is not instrumented.
    Once discovered, the table will be opened normally,
    and instrumented normally.
  */
#endif

  if (open_table_from_share(thd, &share, "" ,0, 0, 0, &table, FALSE))
  {
    free_table_share(&share);
    DBUG_RETURN(3);
  }

  update_create_info_from_table(&create_info, &table);
  create_info.table_options|= HA_OPTION_CREATE_FROM_ENGINE;

  get_canonical_filename(table.file, path, path);
  error=table.file->ha_create(path, &table, &create_info);
  (void) closefrm(&table, 1);

  DBUG_RETURN(error != 0);
}


bool
ha_check_if_table_exists(THD* thd, const char *db, const char *name,
                         bool *exists)
{
  uchar *frmblob= NULL;
  size_t frmlen;
  DBUG_ENTER("ha_check_if_table_exists");

  *exists= ! ha_discover(thd, db, name, &frmblob, &frmlen);
  if (*exists)
    my_free(frmblob);

  DBUG_RETURN(FALSE);
}

bool ha_check_if_supported_system_table(handlerton *hton, const char *db,
                                        const char *table_name)
{
  DBUG_ENTER("ha_check_if_supported_system_table");
  st_sys_tbl_chk_params check_params;
  bool is_system_database= false;
  const char **names;
  st_system_tablename *systab;

  // Check if we have a system database name in the command.
  DBUG_ASSERT(known_system_databases != NULL);
  names= known_system_databases;
  while (names && *names)
  {
    if (strcmp(*names, db) == 0)
    {
      /* Used to compare later, will be faster */
      check_params.db= *names;
      is_system_database= true;
      break;
    }
    names++;
  }
  if (!is_system_database)
    DBUG_RETURN(true); // It's a user table name.

  // Check if this is SQL layer system tables.
  systab= mysqld_system_tables;
  check_params.is_sql_layer_system_table= false;
  while (systab && systab->db)
  {
    if (systab->db == check_params.db &&
        strcmp(systab->tablename, table_name) == 0)
    {
      check_params.is_sql_layer_system_table= true;
      break;
    }
    systab++;
  }

  // Check if this is a system table and if some engine supports it.
  check_params.status= check_params.is_sql_layer_system_table ?
    st_sys_tbl_chk_params::KNOWN_SYSTEM_TABLE :
    st_sys_tbl_chk_params::NOT_KNOWN_SYSTEM_TABLE;
  check_params.db_type= hton->db_type;
  check_params.table_name= table_name;
  plugin_foreach(NULL, check_engine_system_table_handlerton,
                 MYSQL_STORAGE_ENGINE_PLUGIN, &check_params);

  // SE does not support this system table.
  if (check_params.status == st_sys_tbl_chk_params::KNOWN_SYSTEM_TABLE)
    DBUG_RETURN(false);

  // It's a system table or a valid user table.
  DBUG_RETURN(true);
}

static my_bool check_engine_system_table_handlerton(THD *unused,
                                                    plugin_ref plugin,
                                                    void *arg)
{
  st_sys_tbl_chk_params *check_params= (st_sys_tbl_chk_params*) arg;
  handlerton *hton= plugin_data(plugin, handlerton *);

  // Do we already know that the table is a system table?
  if (check_params->status == st_sys_tbl_chk_params::KNOWN_SYSTEM_TABLE)
  {
    /*
      If this is the same SE specified in the command, we can
      simply ask the SE if it supports it stop the search regardless.
    */
    if (hton->db_type == check_params->db_type)
    {
      if (hton->is_supported_system_table &&
          hton->is_supported_system_table(check_params->db,
                                       check_params->table_name,
                                       check_params->is_sql_layer_system_table))
        check_params->status= st_sys_tbl_chk_params::SUPPORTED_SYSTEM_TABLE;
      return TRUE;
    }
    /*
      If this is a different SE, there is no point in asking the SE
      since we already know it's a system table and we don't care
      if it is supported or not.
    */
    return FALSE;
  }

  /*
    We don't yet know if the table is a system table or not.
    We therefore must always ask the SE.
  */
  if (hton->is_supported_system_table &&
      hton->is_supported_system_table(check_params->db,
                                      check_params->table_name,
                                      check_params->is_sql_layer_system_table))
  {
    /*
      If this is the same SE specified in the command, we know it's a
      supported system table and can stop the search.
    */
    if (hton->db_type == check_params->db_type)
    {
      check_params->status= st_sys_tbl_chk_params::SUPPORTED_SYSTEM_TABLE;
      return TRUE;
    }
    else
      check_params->status= st_sys_tbl_chk_params::KNOWN_SYSTEM_TABLE;
  }

  return FALSE;
}

/*
  Prepare list of all known system database names
  current we just have 'mysql' as system database name.

  Later ndbcluster, innodb SE's can define some new database
  name which can store system tables specific to SE.
*/
const char** ha_known_system_databases(void)
{
  list<const char*> found_databases;
  const char **databases, **database;

  // Get mysqld system database name.
  found_databases.push_back((char*) mysqld_system_database);

  // Get system database names from every specific storage engine.
  plugin_foreach(NULL, system_databases_handlerton,
                 MYSQL_STORAGE_ENGINE_PLUGIN, &found_databases);

  databases= (const char **) my_once_alloc(sizeof(char *)*
                                     (found_databases.size()+1),
                                     MYF(MY_WME | MY_FAE));
  DBUG_ASSERT(databases != NULL);

  list<const char*>::iterator it;
  database= databases;
  for (it= found_databases.begin(); it != found_databases.end(); it++)
    *database++= *it;
  *database= 0; // Last element.

  return databases;
}

static my_bool system_databases_handlerton(THD *unused, plugin_ref plugin,
                                           void *arg)
{
  list<const char*> *found_databases= (list<const char*> *) arg;
  const char *db;

  handlerton *hton= plugin_data(plugin, handlerton *);
  if (hton->system_database)
  {
    db= hton->system_database();
    if (db)
      found_databases->push_back(db);
  }

  return FALSE;
}

void st_ha_check_opt::init()
{
  flags= sql_flags= 0;
}


/*****************************************************************************
  Key cache handling.

  This code is only relevant for ISAM/MyISAM tables

  key_cache->cache may be 0 only in the case where a key cache is not
  initialized or when we where not able to init the key cache in a previous
  call to ha_init_key_cache() (probably out of memory)
*****************************************************************************/

int ha_init_key_cache(const char *name, KEY_CACHE *key_cache)
{
  DBUG_ENTER("ha_init_key_cache");

  if (!key_cache->key_cache_inited)
  {
    mysql_mutex_lock(&LOCK_global_system_variables);
    size_t tmp_buff_size= (size_t) key_cache->param_buff_size;
    uint tmp_block_size= (uint) key_cache->param_block_size;
    uint division_limit= key_cache->param_division_limit;
    uint age_threshold=  key_cache->param_age_threshold;
    mysql_mutex_unlock(&LOCK_global_system_variables);
    DBUG_RETURN(!init_key_cache(key_cache,
                                tmp_block_size,
                                tmp_buff_size,
                                division_limit, age_threshold));
  }
  DBUG_RETURN(0);
}


int ha_resize_key_cache(KEY_CACHE *key_cache)
{
  DBUG_ENTER("ha_resize_key_cache");

  if (key_cache->key_cache_inited)
  {
    mysql_mutex_lock(&LOCK_global_system_variables);
    size_t tmp_buff_size= (size_t) key_cache->param_buff_size;
    long tmp_block_size= (long) key_cache->param_block_size;
    uint division_limit= key_cache->param_division_limit;
    uint age_threshold=  key_cache->param_age_threshold;
    mysql_mutex_unlock(&LOCK_global_system_variables);
    DBUG_RETURN(!resize_key_cache(key_cache, tmp_block_size,
                                  tmp_buff_size,
                                  division_limit, age_threshold));
  }
  DBUG_RETURN(0);
}


int ha_change_key_cache_param(KEY_CACHE *key_cache)
{
  if (key_cache->key_cache_inited)
  {
    mysql_mutex_lock(&LOCK_global_system_variables);
    uint division_limit= key_cache->param_division_limit;
    uint age_threshold=  key_cache->param_age_threshold;
    mysql_mutex_unlock(&LOCK_global_system_variables);
    change_key_cache_param(key_cache, division_limit, age_threshold);
  }
  return 0;
}

int ha_change_key_cache(KEY_CACHE *old_key_cache,
                        KEY_CACHE *new_key_cache)
{
  mi_change_key_cache(old_key_cache, new_key_cache);
  return 0;
}


struct st_discover_args
{
  const char *db;
  const char *name;
  uchar **frmblob; 
  size_t *frmlen;
};

static my_bool discover_handlerton(THD *thd, plugin_ref plugin,
                                   void *arg)
{
  st_discover_args *vargs= (st_discover_args *)arg;
  handlerton *hton= plugin_data(plugin, handlerton *);
  if (hton->state == SHOW_OPTION_YES && hton->discover &&
      (!(hton->discover(hton, thd, vargs->db, vargs->name, 
                        vargs->frmblob, 
                        vargs->frmlen))))
    return TRUE;

  return FALSE;
}

int ha_discover(THD *thd, const char *db, const char *name,
                uchar **frmblob, size_t *frmlen)
{
  int error= -1; // Table does not exist in any handler
  DBUG_ENTER("ha_discover");
  DBUG_PRINT("enter", ("db: %s, name: %s", db, name));
  st_discover_args args= {db, name, frmblob, frmlen};

  if (is_prefix(name,tmp_file_prefix)) /* skip temporary tables */
    DBUG_RETURN(error);

  if (plugin_foreach(thd, discover_handlerton,
                 MYSQL_STORAGE_ENGINE_PLUGIN, &args))
    error= 0;

  if (!error)
    status_var_increment(thd->status_var.ha_discover_count);
  DBUG_RETURN(error);
}


struct st_find_files_args
{
  const char *db;
  const char *path;
  const char *wild;
  bool dir;
  List<LEX_STRING> *files;
};

static my_bool find_files_handlerton(THD *thd, plugin_ref plugin,
                                   void *arg)
{
  st_find_files_args *vargs= (st_find_files_args *)arg;
  handlerton *hton= plugin_data(plugin, handlerton *);


  if (hton->state == SHOW_OPTION_YES && hton->find_files)
      if (hton->find_files(hton, thd, vargs->db, vargs->path, vargs->wild, 
                          vargs->dir, vargs->files))
        return TRUE;

  return FALSE;
}

int
ha_find_files(THD *thd,const char *db,const char *path,
              const char *wild, bool dir, List<LEX_STRING> *files)
{
  int error= 0;
  DBUG_ENTER("ha_find_files");
  DBUG_PRINT("enter", ("db: '%s'  path: '%s'  wild: '%s'  dir: %d", 
                       db, path, wild ? wild : "NULL", dir));
  st_find_files_args args= {db, path, wild, dir, files};

  plugin_foreach(thd, find_files_handlerton,
                 MYSQL_STORAGE_ENGINE_PLUGIN, &args);
  /* The return value is not currently used */
  DBUG_RETURN(error);
}

struct st_table_exists_in_engine_args
{
  const char *db;
  const char *name;
  int err;
};

static my_bool table_exists_in_engine_handlerton(THD *thd, plugin_ref plugin,
                                   void *arg)
{
  st_table_exists_in_engine_args *vargs= (st_table_exists_in_engine_args *)arg;
  handlerton *hton= plugin_data(plugin, handlerton *);

  int err= HA_ERR_NO_SUCH_TABLE;

  if (hton->state == SHOW_OPTION_YES && hton->table_exists_in_engine)
    err = hton->table_exists_in_engine(hton, thd, vargs->db, vargs->name);

  vargs->err = err;
  if (vargs->err == HA_ERR_TABLE_EXIST)
    return TRUE;

  return FALSE;
}

int ha_table_exists_in_engine(THD* thd, const char* db, const char* name)
{
  DBUG_ENTER("ha_table_exists_in_engine");
  DBUG_PRINT("enter", ("db: %s, name: %s", db, name));
  st_table_exists_in_engine_args args= {db, name, HA_ERR_NO_SUCH_TABLE};
  plugin_foreach(thd, table_exists_in_engine_handlerton,
                 MYSQL_STORAGE_ENGINE_PLUGIN, &args);
  DBUG_PRINT("exit", ("error: %d", args.err));
  DBUG_RETURN(args.err);
}

struct st_make_pushed_join_args
{
  const AQP::Join_plan* plan; // Query plan provided by optimizer
  int err;                    // Error code to return.
};

static my_bool make_pushed_join_handlerton(THD *thd, plugin_ref plugin,
                                   void *arg)
{
  st_make_pushed_join_args *vargs= (st_make_pushed_join_args *)arg;
  handlerton *hton= plugin_data(plugin, handlerton *);

  if (hton && hton->make_pushed_join)
  {
    const int error= hton->make_pushed_join(hton, thd, vargs->plan);
    if (unlikely(error))
    {
      vargs->err = error;
      return TRUE;
    }
  }
  return FALSE;
}

int ha_make_pushed_joins(THD *thd, const AQP::Join_plan* plan)
{
  DBUG_ENTER("ha_make_pushed_joins");
  st_make_pushed_join_args args= {plan, 0};
  plugin_foreach(thd, make_pushed_join_handlerton,
                 MYSQL_STORAGE_ENGINE_PLUGIN, &args);
  DBUG_PRINT("exit", ("error: %d", args.err));
  DBUG_RETURN(args.err);
}

/*
  TODO: change this into a dynamic struct
  List<handlerton> does not work as
  1. binlog_end is called when MEM_ROOT is gone
  2. cannot work with thd MEM_ROOT as memory should be freed
*/
#define MAX_HTON_LIST_ST 63
struct hton_list_st
{
  handlerton *hton[MAX_HTON_LIST_ST];
  uint sz;
};

struct binlog_func_st
{
  enum_binlog_func fn;
  void *arg;
};

static my_bool binlog_func_list(THD *thd, plugin_ref plugin, void *arg)
{
  hton_list_st *hton_list= (hton_list_st *)arg;
  handlerton *hton= plugin_data(plugin, handlerton *);
  if (hton->state == SHOW_OPTION_YES && hton->binlog_func)
  {
    uint sz= hton_list->sz;
    if (sz == MAX_HTON_LIST_ST-1)
    {
      /* list full */
      return FALSE;
    }
    hton_list->hton[sz]= hton;
    hton_list->sz= sz+1;
  }
  return FALSE;
}

static my_bool binlog_func_foreach(THD *thd, binlog_func_st *bfn)
{
  hton_list_st hton_list;
  uint i, sz;

  hton_list.sz= 0;
  plugin_foreach(thd, binlog_func_list,
                 MYSQL_STORAGE_ENGINE_PLUGIN, &hton_list);

  for (i= 0, sz= hton_list.sz; i < sz ; i++)
    hton_list.hton[i]->binlog_func(hton_list.hton[i], thd, bfn->fn, bfn->arg);
  return FALSE;
}

#ifdef HAVE_NDB_BINLOG

int ha_reset_logs(THD *thd)
{
  binlog_func_st bfn= {BFN_RESET_LOGS, 0};
  binlog_func_foreach(thd, &bfn);
  return 0;
}

void ha_reset_slave(THD* thd)
{
  binlog_func_st bfn= {BFN_RESET_SLAVE, 0};
  binlog_func_foreach(thd, &bfn);
}

void ha_binlog_wait(THD* thd)
{
  binlog_func_st bfn= {BFN_BINLOG_WAIT, 0};
  binlog_func_foreach(thd, &bfn);
}

int ha_binlog_index_purge_file(THD *thd, const char *file)
{
  binlog_func_st bfn= {BFN_BINLOG_PURGE_FILE, (void *)file};
  binlog_func_foreach(thd, &bfn);
  return 0;
}

struct binlog_log_query_st
{
  enum_binlog_command binlog_command;
  const char *query;
  uint query_length;
  const char *db;
  const char *table_name;
};

static my_bool binlog_log_query_handlerton2(THD *thd,
                                            handlerton *hton,
                                            void *args)
{
  struct binlog_log_query_st *b= (struct binlog_log_query_st*)args;
  if (hton->state == SHOW_OPTION_YES && hton->binlog_log_query)
    hton->binlog_log_query(hton, thd,
                           b->binlog_command,
                           b->query,
                           b->query_length,
                           b->db,
                           b->table_name);
  return FALSE;
}

static my_bool binlog_log_query_handlerton(THD *thd,
                                           plugin_ref plugin,
                                           void *args)
{
  return binlog_log_query_handlerton2(thd, plugin_data(plugin, handlerton *), args);
}

void ha_binlog_log_query(THD *thd, handlerton *hton,
                         enum_binlog_command binlog_command,
                         const char *query, uint query_length,
                         const char *db, const char *table_name)
{
  struct binlog_log_query_st b;
  b.binlog_command= binlog_command;
  b.query= query;
  b.query_length= query_length;
  b.db= db;
  b.table_name= table_name;
  if (hton == 0)
    plugin_foreach(thd, binlog_log_query_handlerton,
                   MYSQL_STORAGE_ENGINE_PLUGIN, &b);
  else
    binlog_log_query_handlerton2(thd, hton, &b);
}
#endif

int ha_binlog_end(THD* thd)
{
  binlog_func_st bfn= {BFN_BINLOG_END, 0};
  binlog_func_foreach(thd, &bfn);
  return 0;
}

double handler::index_only_read_time(uint keynr, double records)
{
  double read_time;
  uint keys_per_block= (stats.block_size/2/
                        (table_share->key_info[keynr].key_length + ref_length) +
                        1);
  read_time=((double) (records + keys_per_block-1) /
             (double) keys_per_block);
  return read_time;
}


bool key_uses_partial_cols(TABLE *table, uint keyno)
{
  KEY_PART_INFO *kp= table->key_info[keyno].key_part;
  KEY_PART_INFO *kp_end= kp + table->key_info[keyno].user_defined_key_parts;
  for (; kp != kp_end; kp++)
  {
    if (!kp->field->part_of_key.is_set(keyno))
      return TRUE;
  }
  return FALSE;
}

/****************************************************************************
 * Default MRR implementation (MRR to non-MRR converter)
 ***************************************************************************/

ha_rows 
handler::multi_range_read_info_const(uint keyno, RANGE_SEQ_IF *seq,
                                     void *seq_init_param, uint n_ranges_arg,
                                     uint *bufsz, uint *flags, 
                                     Cost_estimate *cost)
{
  KEY_MULTI_RANGE range;
  range_seq_t seq_it;
  ha_rows rows, total_rows= 0;
  uint n_ranges=0;
  THD *thd= current_thd;
  
  /* Default MRR implementation doesn't need buffer */
  *bufsz= 0;

  DBUG_EXECUTE_IF("bug13822652_2", thd->killed= THD::KILL_QUERY;);

  seq_it= seq->init(seq_init_param, n_ranges, *flags);
  while (!seq->next(seq_it, &range))
  {
    if (unlikely(thd->killed != 0))
      return HA_POS_ERROR;
    
    n_ranges++;
    key_range *min_endp, *max_endp;
    if (range.range_flag & GEOM_FLAG)
    {
      /* In this case tmp_min_flag contains the handler-read-function */
      range.start_key.flag= (ha_rkey_function) (range.range_flag ^ GEOM_FLAG);
      min_endp= &range.start_key;
      max_endp= NULL;
    }
    else
    {
      min_endp= range.start_key.length? &range.start_key : NULL;
      max_endp= range.end_key.length? &range.end_key : NULL;
    }
    /*
      Get the number of rows in the range. This is done by calling
      records_in_range() unless:

        1) The range is an equality range and the index is unique.
           There cannot be more than one matching row, so 1 is
           assumed. Note that it is possible that the correct number
           is actually 0, so the row estimate may be too high in this
           case. Also note: ranges of the form "x IS NULL" may have more
           than 1 mathing row so records_in_range() is called for these.
        2) a) The range is an equality range but the index is either 
              not unique or all of the keyparts are not used. 
           b) The user has requested that index statistics should be used
              for equality ranges to avoid the incurred overhead of 
              index dives in records_in_range().
           c) Index statistics is available.
           Ranges of the form "x IS NULL" will not use index statistics 
           because the number of rows with this value are likely to be 
           very different than the values in the index statistics.
    */
    int keyparts_used= 0;
    if ((range.range_flag & UNIQUE_RANGE) &&                        // 1)
        !(range.range_flag & NULL_RANGE))
      rows= 1; /* there can be at most one row */
    else if ((range.range_flag & EQ_RANGE) &&                       // 2a)
             (range.range_flag & USE_INDEX_STATISTICS) &&           // 2b)
             (keyparts_used= my_count_bits(range.start_key.keypart_map)) &&
             table->key_info[keyno].rec_per_key[keyparts_used-1] && // 2c)
             !(range.range_flag & NULL_RANGE))
      rows= table->key_info[keyno].rec_per_key[keyparts_used-1];
    else
    {
      DBUG_EXECUTE_IF("crash_records_in_range", DBUG_SUICIDE(););
      DBUG_ASSERT(min_endp || max_endp);
      if (HA_POS_ERROR == (rows= this->records_in_range(keyno, min_endp, 
                                                        max_endp)))
      {
        /* Can't scan one range => can't do MRR scan at all */
        total_rows= HA_POS_ERROR;
        break;
      }
    }
    total_rows += rows;
  }
  
  if (total_rows != HA_POS_ERROR)
  {
    /* The following calculation is the same as in multi_range_read_info(): */
    *flags|= HA_MRR_USE_DEFAULT_IMPL;
    *flags|= HA_MRR_SUPPORT_SORTED;

    DBUG_ASSERT(cost->is_zero());
    if ((*flags & HA_MRR_INDEX_ONLY) && total_rows > 2)
      cost->add_io(index_only_read_time(keyno, total_rows) *
                   Cost_estimate::IO_BLOCK_READ_COST());
    else
      cost->add_io(read_time(keyno, n_ranges, total_rows) *
                   Cost_estimate::IO_BLOCK_READ_COST());
    cost->add_cpu(total_rows * ROW_EVALUATE_COST + 0.01);
  }
  return total_rows;
}


ha_rows handler::multi_range_read_info(uint keyno, uint n_ranges, uint n_rows,
                                       uint *bufsz, uint *flags, 
                                       Cost_estimate *cost)
{
  *bufsz= 0; /* Default implementation doesn't need a buffer */

  *flags|= HA_MRR_USE_DEFAULT_IMPL;
  *flags|= HA_MRR_SUPPORT_SORTED;

  DBUG_ASSERT(cost->is_zero());

  /* Produce the same cost as non-MRR code does */
  if (*flags & HA_MRR_INDEX_ONLY)
    cost->add_io(index_only_read_time(keyno, n_rows) * 
                 Cost_estimate::IO_BLOCK_READ_COST());
  else
    cost->add_io(read_time(keyno, n_ranges, n_rows) *
                 Cost_estimate::IO_BLOCK_READ_COST());
  return 0;
}


int
handler::multi_range_read_init(RANGE_SEQ_IF *seq_funcs, void *seq_init_param,
                               uint n_ranges, uint mode, HANDLER_BUFFER *buf)
{
  DBUG_ENTER("handler::multi_range_read_init");
  mrr_iter= seq_funcs->init(seq_init_param, n_ranges, mode);
  mrr_funcs= *seq_funcs;
  mrr_is_output_sorted= test(mode & HA_MRR_SORTED);
  mrr_have_range= FALSE;
  DBUG_RETURN(0);
}


int handler::multi_range_read_next(char **range_info)
{
  int result= HA_ERR_END_OF_FILE;
  int range_res;
  DBUG_ENTER("handler::multi_range_read_next");

  if (!mrr_have_range)
  {
    mrr_have_range= TRUE;
    goto start;
  }

  do
  {
    /* Save a call if there can be only one row in range. */
    if (mrr_cur_range.range_flag != (UNIQUE_RANGE | EQ_RANGE))
    {
      result= read_range_next();
      /* On success or non-EOF errors jump to the end. */
      if (result != HA_ERR_END_OF_FILE)
        break;
    }
    else
    {
      if (was_semi_consistent_read())
        goto scan_it_again;
    }

start:
    /* Try the next range(s) until one matches a record. */
    while (!(range_res= mrr_funcs.next(mrr_iter, &mrr_cur_range)))
    {
scan_it_again:
      result= read_range_first(mrr_cur_range.start_key.keypart_map ?
                                 &mrr_cur_range.start_key : 0,
                               mrr_cur_range.end_key.keypart_map ?
                                 &mrr_cur_range.end_key : 0,
                               test(mrr_cur_range.range_flag & EQ_RANGE),
                               mrr_is_output_sorted);
      if (result != HA_ERR_END_OF_FILE)
        break;
    }
  }
  while ((result == HA_ERR_END_OF_FILE) && !range_res);

  *range_info= mrr_cur_range.ptr;
  DBUG_PRINT("exit",("handler::multi_range_read_next result %d", result));
  DBUG_RETURN(result);
}


/****************************************************************************
 * DS-MRR implementation 
 ***************************************************************************/

int DsMrr_impl::dsmrr_init(handler *h_arg, RANGE_SEQ_IF *seq_funcs, 
                           void *seq_init_param, uint n_ranges, uint mode,
                           HANDLER_BUFFER *buf)
{
  uint elem_size;
  int retval= 0;
  DBUG_ENTER("DsMrr_impl::dsmrr_init");
  THD *thd= h_arg->table->in_use;     // current THD

  /*
    index_merge may invoke a scan on an object for which dsmrr_info[_const]
    has not been called, so set the owner handler here as well.
  */
  h= h_arg;
  if (!thd->optimizer_switch_flag(OPTIMIZER_SWITCH_MRR) ||
      mode & (HA_MRR_USE_DEFAULT_IMPL | HA_MRR_SORTED)) // DS-MRR doesn't sort
  {
    use_default_impl= TRUE;
    retval= h->handler::multi_range_read_init(seq_funcs, seq_init_param,
                                              n_ranges, mode, buf);
    DBUG_RETURN(retval);
  }

  /* 
    This assert will hit if we have pushed an index condition to the
    primary key index and then "change our mind" and use a different
    index for retrieving data with MRR. One of the following criteria
    must be true:
      1. We have not pushed an index conditon on this handler.
      2. We have pushed an index condition and this is on the currently used
         index.
      3. We have pushed an index condition but this is not for the primary key.
      4. We have pushed an index condition and this has been transferred to 
         the clone (h2) of the handler object.
  */
  DBUG_ASSERT(!h->pushed_idx_cond ||
              h->pushed_idx_cond_keyno == h->active_index ||
              h->pushed_idx_cond_keyno != table->s->primary_key ||
              (h2 && h->pushed_idx_cond_keyno == h2->active_index));

  rowids_buf= buf->buffer;

  is_mrr_assoc= !test(mode & HA_MRR_NO_ASSOCIATION);

  if (is_mrr_assoc)
    status_var_increment(table->in_use->status_var.ha_multi_range_read_init_count);
 
  rowids_buf_end= buf->buffer_end;
  elem_size= h->ref_length + (int)is_mrr_assoc * sizeof(void*);
  rowids_buf_last= rowids_buf + 
                      ((rowids_buf_end - rowids_buf)/ elem_size)*
                      elem_size;
  rowids_buf_end= rowids_buf_last;

  /*
    The DS-MRR scan uses a second handler object (h2) for doing the
    index scan. Create this by cloning the primary handler
    object. The h2 handler object is deleted when DsMrr_impl::reset()
    is called.
  */
  if (!h2)
  {
    handler *new_h2;
    /*
      ::clone() takes up a lot of stack, especially on 64 bit platforms.
      The constant 5 is an empiric result.
      @todo Is this still the case? Leave it as it is for now but could
            likely be removed?
    */
    if (check_stack_overrun(thd, 5*STACK_MIN_SIZE, (uchar*) &new_h2))
      DBUG_RETURN(1);

    if (!(new_h2= h->clone(h->table->s->normalized_path.str, thd->mem_root)))
      DBUG_RETURN(1);
    h2= new_h2; /* Ok, now can put it into h2 */
    table->prepare_for_position();
  }

  /*
    Open the index scan on h2 using the key from the primary handler.
  */
  if (h2->active_index == MAX_KEY)
  {
    DBUG_ASSERT(h->active_index != MAX_KEY);
    const uint mrr_keyno= h->active_index;

    if ((retval= h2->ha_external_lock(thd, h->m_lock_type)))
      goto error;

    if ((retval= h2->extra(HA_EXTRA_KEYREAD)))
      goto error;

    if ((retval= h2->ha_index_init(mrr_keyno, false)))
      goto error;

    // Transfer ICP from h to h2
    if (mrr_keyno == h->pushed_idx_cond_keyno)
    {
      if (h2->idx_cond_push(mrr_keyno, h->pushed_idx_cond))
      {
        retval= 1;
        goto error;
      }
    }
    else
    {
      // Cancel any potentially previously pushed index conditions
      h2->cancel_pushed_idx_cond();
    }
  }
  else
  {
    /*
      h2 has already an open index. This happens when the DS-MRR scan
      is re-started without closing it first. In this case the primary
      handler must be used for reading records from the table, ie. it
      must not be opened for doing a new range scan. In this case
      the active_index must either not be set or be the primary key.
    */
    DBUG_ASSERT(h->inited == handler::RND);
    DBUG_ASSERT(h->active_index == MAX_KEY || 
                h->active_index == table->s->primary_key);
  }

  /*
    The index scan is now transferred to h2 and we can close the open
    index scan on the primary handler.
  */
  if (h->inited == handler::INDEX)
  {
    /*
      Calling h->ha_index_end() will invoke dsmrr_close() for this object,
      which will close the index scan on h2. We need to keep it open, so 
      temporarily move h2 out of the DsMrr object.
    */
    handler *save_h2= h2;
    h2= NULL;
    retval= h->ha_index_end();
    h2= save_h2;
    if (retval)
      goto error;
  }

  /*
    Verify consistency between h and h2.
  */
  DBUG_ASSERT(h->inited != handler::INDEX);
  DBUG_ASSERT(h->active_index == MAX_KEY || 
              h->active_index == table->s->primary_key);
  DBUG_ASSERT(h2->inited == handler::INDEX);
  DBUG_ASSERT(h2->active_index != MAX_KEY);
  DBUG_ASSERT(h->m_lock_type == h2->m_lock_type);

  if ((retval= h2->handler::multi_range_read_init(seq_funcs, seq_init_param, 
                                                  n_ranges, mode, buf)))
    goto error;

  if ((retval= dsmrr_fill_buffer()))
    goto error;

  /*
    If the above call has scanned through all intervals in *seq, then
    adjust *buf to indicate that the remaining buffer space will not be used.
  */
  if (dsmrr_eof) 
    buf->end_of_used_area= rowids_buf_last;

  /*
     h->inited == INDEX may occur when 'range checked for each record' is
     used.
  */
  if ((h->inited != handler::RND) && 
      ((h->inited==handler::INDEX? h->ha_index_end(): FALSE) || 
       (h->ha_rnd_init(FALSE))))
  {
    retval= 1;
    goto error;
  }

  use_default_impl= FALSE;
  h->mrr_funcs= *seq_funcs;
  
  DBUG_RETURN(0);
error:
  h2->ha_index_or_rnd_end();
  h2->ha_external_lock(thd, F_UNLCK);
  h2->close();
  delete h2;
  h2= NULL;
  DBUG_ASSERT(retval != 0);
  DBUG_RETURN(retval);
}


void DsMrr_impl::dsmrr_close()
{
  DBUG_ENTER("DsMrr_impl::dsmrr_close");

  // If there is an open index on h2, then close it
  if (h2 && h2->active_index != MAX_KEY)
  {
    h2->ha_index_or_rnd_end();
    h2->ha_external_lock(current_thd, F_UNLCK);
  }
  use_default_impl= true;
  DBUG_VOID_RETURN;
}


void DsMrr_impl::reset()
{
  DBUG_ENTER("DsMrr_impl::reset");

  if (h2)
  {
    // Close any ongoing DS-MRR scan 
    dsmrr_close();

    // Close and delete the h2 handler
    h2->close();
    delete h2;
    h2= NULL;
  }
  DBUG_VOID_RETURN;
}


static int rowid_cmp(void *h, uchar *a, uchar *b)
{
  return ((handler*)h)->cmp_ref(a, b);
}


int DsMrr_impl::dsmrr_fill_buffer()
{
  char *range_info;
  int res= 0;
  DBUG_ENTER("DsMrr_impl::dsmrr_fill_buffer");
  DBUG_ASSERT(rowids_buf < rowids_buf_end);

  rowids_buf_cur= rowids_buf;
  while ((rowids_buf_cur < rowids_buf_end) && 
         !(res= h2->handler::multi_range_read_next(&range_info)))
  {
    KEY_MULTI_RANGE *curr_range= &h2->handler::mrr_cur_range;
    if (h2->mrr_funcs.skip_index_tuple &&
        h2->mrr_funcs.skip_index_tuple(h2->mrr_iter, curr_range->ptr))
      continue;
    
    /* Put rowid, or {rowid, range_id} pair into the buffer */
    h2->position(table->record[0]);
    memcpy(rowids_buf_cur, h2->ref, h2->ref_length);
    rowids_buf_cur += h2->ref_length;

    if (is_mrr_assoc)
    {
      memcpy(rowids_buf_cur, &range_info, sizeof(void*));
      rowids_buf_cur += sizeof(void*);
    }
  }

  if (res && res != HA_ERR_END_OF_FILE)
    DBUG_RETURN(res); 
  dsmrr_eof= test(res == HA_ERR_END_OF_FILE);

  /* Sort the buffer contents by rowid */
  uint elem_size= h->ref_length + (int)is_mrr_assoc * sizeof(void*);
  uint n_rowids= (rowids_buf_cur - rowids_buf) / elem_size;
  
  my_qsort2(rowids_buf, n_rowids, elem_size, (qsort2_cmp)rowid_cmp,
            (void*)h);
  rowids_buf_last= rowids_buf_cur;
  rowids_buf_cur=  rowids_buf;
  DBUG_RETURN(0);
}


/*
  DS-MRR implementation: multi_range_read_next() function
*/

int DsMrr_impl::dsmrr_next(char **range_info)
{
  int res;
  uchar *cur_range_info= 0;
  uchar *rowid;

  if (use_default_impl)
    return h->handler::multi_range_read_next(range_info);
  
  do
  {
    if (rowids_buf_cur == rowids_buf_last)
    {
      if (dsmrr_eof)
      {
        res= HA_ERR_END_OF_FILE;
        goto end;
      }

      res= dsmrr_fill_buffer();
      if (res)
        goto end;
    }
   
    /* return eof if there are no rowids in the buffer after re-fill attempt */
    if (rowids_buf_cur == rowids_buf_last)
    {
      res= HA_ERR_END_OF_FILE;
      goto end;
    }
    rowid= rowids_buf_cur;

    if (is_mrr_assoc)
      memcpy(&cur_range_info, rowids_buf_cur + h->ref_length, sizeof(uchar*));

    rowids_buf_cur += h->ref_length + sizeof(void*) * test(is_mrr_assoc);
    if (h2->mrr_funcs.skip_record &&
        h2->mrr_funcs.skip_record(h2->mrr_iter, (char *) cur_range_info, rowid))
      continue;
    res= h->rnd_pos(table->record[0], rowid);
    break;
  } while (true);
 
  if (is_mrr_assoc)
  {
    memcpy(range_info, rowid + h->ref_length, sizeof(void*));
  }
end:
  return res;
}


/*
  DS-MRR implementation: multi_range_read_info() function
*/
ha_rows DsMrr_impl::dsmrr_info(uint keyno, uint n_ranges, uint rows,
                               uint *bufsz, uint *flags, Cost_estimate *cost)
{  
  ha_rows res;
  uint def_flags= *flags;
  uint def_bufsz= *bufsz;

  /* Get cost/flags/mem_usage of default MRR implementation */
  res= h->handler::multi_range_read_info(keyno, n_ranges, rows, &def_bufsz,
                                         &def_flags, cost);
  DBUG_ASSERT(!res);

  if ((*flags & HA_MRR_USE_DEFAULT_IMPL) || 
      choose_mrr_impl(keyno, rows, flags, bufsz, cost))
  {
    /* Default implementation is choosen */
    DBUG_PRINT("info", ("Default MRR implementation choosen"));
    *flags= def_flags;
    *bufsz= def_bufsz;
    DBUG_ASSERT(*flags & HA_MRR_USE_DEFAULT_IMPL);
  }
  else
  {
    /* *flags and *bufsz were set by choose_mrr_impl */
    DBUG_PRINT("info", ("DS-MRR implementation choosen"));
  }
  return 0;
}


/*
  DS-MRR Implementation: multi_range_read_info_const() function
*/

ha_rows DsMrr_impl::dsmrr_info_const(uint keyno, RANGE_SEQ_IF *seq,
                                 void *seq_init_param, uint n_ranges, 
                                 uint *bufsz, uint *flags, Cost_estimate *cost)
{
  ha_rows rows;
  uint def_flags= *flags;
  uint def_bufsz= *bufsz;
  /* Get cost/flags/mem_usage of default MRR implementation */
  rows= h->handler::multi_range_read_info_const(keyno, seq, seq_init_param,
                                                n_ranges, &def_bufsz, 
                                                &def_flags, cost);
  if (rows == HA_POS_ERROR)
  {
    /* Default implementation can't perform MRR scan => we can't either */
    return rows;
  }

  /*
    If HA_MRR_USE_DEFAULT_IMPL has been passed to us, that is an order to
    use the default MRR implementation (we need it for UPDATE/DELETE).
    Otherwise, make a choice based on cost and mrr* flags of
    @@optimizer_switch.
  */
  if ((*flags & HA_MRR_USE_DEFAULT_IMPL) ||
      choose_mrr_impl(keyno, rows, flags, bufsz, cost))
  {
    DBUG_PRINT("info", ("Default MRR implementation choosen"));
    *flags= def_flags;
    *bufsz= def_bufsz;
    DBUG_ASSERT(*flags & HA_MRR_USE_DEFAULT_IMPL);
  }
  else
  {
    /* *flags and *bufsz were set by choose_mrr_impl */
    DBUG_PRINT("info", ("DS-MRR implementation choosen"));
  }
  return rows;
}


bool DsMrr_impl::choose_mrr_impl(uint keyno, ha_rows rows, uint *flags,
                                 uint *bufsz, Cost_estimate *cost)
{
  bool res;
  THD *thd= current_thd;
  if (!thd->optimizer_switch_flag(OPTIMIZER_SWITCH_MRR) ||
      *flags & (HA_MRR_INDEX_ONLY | HA_MRR_SORTED) || // Unsupported by DS-MRR
      (keyno == table->s->primary_key && h->primary_key_is_clustered()) ||
       key_uses_partial_cols(table, keyno))
  {
    /* Use the default implementation, don't modify args: See comments  */
    return TRUE;
  }

  /*
    If @@optimizer_switch has "mrr_cost_based" on, we should avoid
    using DS-MRR for queries where it is likely that the records are
    stored in memory. Since there is currently no way to determine
    this, we use a heuristic:
    a) if the storage engine has a memory buffer, DS-MRR is only
       considered if the table size is bigger than the buffer.
    b) if the storage engine does not have a memory buffer, DS-MRR is
       only considered if the table size is bigger than 100MB.
    c) Since there is an initial setup cost of DS-MRR, so it is only
       considered if at least 50 records will be read.
  */
  if (thd->optimizer_switch_flag(OPTIMIZER_SWITCH_MRR_COST_BASED))
  {
    /*
      If the storage engine has a database buffer we use this as the
      minimum size the table should have before considering DS-MRR.
    */ 
    longlong min_file_size= table->file->get_memory_buffer_size();
    if (min_file_size == -1)
    {
      // No estimate for database buffer
      min_file_size= 100 * 1024 * 1024;    // 100 MB
    }

    if (table->file->stats.data_file_length < 
        static_cast<ulonglong>(min_file_size) ||
        rows <= 50)
      return true;                 // Use the default implementation 
  }

  Cost_estimate dsmrr_cost;
  if (get_disk_sweep_mrr_cost(keyno, rows, *flags, bufsz, &dsmrr_cost))
    return TRUE;
  
  bool force_dsmrr;
  /* 
    If @@optimizer_switch has "mrr" on and "mrr_cost_based" off, then set cost
    of DS-MRR to be minimum of DS-MRR and Default implementations cost. This
    allows one to force use of DS-MRR whenever it is applicable without
    affecting other cost-based choices.
  */
  if ((force_dsmrr=
       (thd->optimizer_switch_flag(OPTIMIZER_SWITCH_MRR) &&
        !thd->optimizer_switch_flag(OPTIMIZER_SWITCH_MRR_COST_BASED))) &&
      dsmrr_cost.total_cost() > cost->total_cost())
    dsmrr_cost= *cost;

  if (force_dsmrr || (dsmrr_cost.total_cost() <= cost->total_cost()))
  {
    *flags &= ~HA_MRR_USE_DEFAULT_IMPL;  /* Use the DS-MRR implementation */
    *flags &= ~HA_MRR_SUPPORT_SORTED;    /* We can't provide ordered output */
    *cost= dsmrr_cost;
    res= FALSE;
  }
  else
  {
    /* Use the default MRR implementation */
    res= TRUE;
  }
  return res;
}


static void get_sort_and_sweep_cost(TABLE *table, ha_rows nrows, 
                                    Cost_estimate *cost);


bool DsMrr_impl::get_disk_sweep_mrr_cost(uint keynr, ha_rows rows, uint flags,
                                         uint *buffer_size, 
                                         Cost_estimate *cost)
{
  ha_rows rows_in_last_step;
  uint n_full_steps;
  double index_read_cost;

  const uint elem_size= h->ref_length + 
                        sizeof(void*) * (!test(flags & HA_MRR_NO_ASSOCIATION));
  const ha_rows max_buff_entries= *buffer_size / elem_size;

  if (!max_buff_entries)
    return TRUE; /* Buffer has not enough space for even 1 rowid */

  /* Number of iterations we'll make with full buffer */
  n_full_steps= (uint)floor(rows2double(rows) / max_buff_entries);

  /*
    Get numbers of rows we'll be processing in last iteration, with
    non-full buffer
  */
  rows_in_last_step= rows % max_buff_entries;
  
  DBUG_ASSERT(cost->is_zero());

  if (n_full_steps)
  {
    get_sort_and_sweep_cost(table, max_buff_entries, cost);
    cost->multiply(n_full_steps);
  }
  else
  {
    /* 
      Adjust buffer size since only parts of the buffer will be used:
      1. Adjust record estimate for the last scan to reduce likelyhood
         of needing more than one scan by adding 20 percent to the
         record estimate and by ensuring this is at least 100 records.
      2. If the estimated needed buffer size is lower than suggested by 
         the caller then set it to the estimated buffer size.
    */
    const ha_rows keys_in_buffer=
      max<ha_rows>(static_cast<ha_rows>(1.2 * rows_in_last_step), 100);
    *buffer_size= min<ulong>(*buffer_size,
                             static_cast<ulong>(keys_in_buffer) * elem_size);
  }

  Cost_estimate last_step_cost;
  get_sort_and_sweep_cost(table, rows_in_last_step, &last_step_cost);
  (*cost)+= last_step_cost;

  /*
    Cost of memory is not included in the total_cost() function and
    thus will not be considered when comparing costs. Still, we
    record it in the cost estimate object for future use.
  */
  cost->add_mem(*buffer_size);

  /* Total cost of all index accesses */
  index_read_cost= h->index_only_read_time(keynr, rows);
  cost->add_io(index_read_cost * Cost_estimate::IO_BLOCK_READ_COST());

  /*
    Add CPU cost for processing records (see
    @handler::multi_range_read_info_const()).
  */
  cost->add_cpu(rows * ROW_EVALUATE_COST);
  return FALSE;
}


/* 
  Get cost of one sort-and-sweep step

  SYNOPSIS
    get_sort_and_sweep_cost()
      table       Table being accessed
      nrows       Number of rows to be sorted and retrieved
      cost   OUT  The cost

  DESCRIPTION
    Get cost of these operations:
     - sort an array of #nrows ROWIDs using qsort
     - read #nrows records from table in a sweep.
*/

static 
void get_sort_and_sweep_cost(TABLE *table, ha_rows nrows, Cost_estimate *cost)
{
  DBUG_ASSERT(cost->is_zero());
  if (nrows)
  {
    get_sweep_read_cost(table, nrows, FALSE, cost);

    /* 
      Constant for the cost of doing one key compare operation in the
      sort operation. We should have used the existing
      ROWID_COMPARE_COST constant here but this would make the cost
      estimate of sorting very high for queries accessing many
      records. Until this constant is adjusted we introduce a constant
      that is more realistic. @todo: Replace this with
      ROWID_COMPARE_COST when this have been given a realistic value.
    */
    const double ROWID_COMPARE_SORT_COST = 0.01;

    /* Add cost of qsort call: n * log2(n) * cost(rowid_comparison) */
    const double cpu_sort= nrows * log2(nrows) * ROWID_COMPARE_SORT_COST;
    cost->add_cpu(cpu_sort);
  }
}


void get_sweep_read_cost(TABLE *table, ha_rows nrows, bool interrupted, 
                         Cost_estimate *cost)
{
  DBUG_ENTER("get_sweep_read_cost");

  DBUG_ASSERT(cost->is_zero());
  if(nrows > 0)
  {
    double n_blocks=
      ceil(ulonglong2double(table->file->stats.data_file_length) / IO_SIZE);
    if (n_blocks < 1.0)                         // When data_file_length is 0
      n_blocks= 1.0;
    double busy_blocks=
      n_blocks * (1.0 - pow(1.0 - 1.0/n_blocks, rows2double(nrows)));
    if (busy_blocks < 1.0)
      busy_blocks= 1.0;

    DBUG_PRINT("info",("sweep: nblocks=%g, busy_blocks=%g", n_blocks,
                       busy_blocks));
    if (interrupted)
      cost->add_io(busy_blocks * Cost_estimate::IO_BLOCK_READ_COST());
    else
      /* Assume reading is done in one 'sweep' */
      cost->add_io(busy_blocks * 
                   (DISK_SEEK_BASE_COST +
                    DISK_SEEK_PROP_COST * n_blocks / busy_blocks));
  }
  DBUG_PRINT("info",("returning cost=%g", cost->total_cost()));
  DBUG_VOID_RETURN;
}


/****************************************************************************
 * DS-MRR implementation ends
 ***************************************************************************/

int handler::read_range_first(const key_range *start_key,
                              const key_range *end_key,
                              bool eq_range_arg,
                              bool sorted /* ignored */)
{
  int result;
  DBUG_ENTER("handler::read_range_first");

  eq_range= eq_range_arg;
  set_end_range(end_key, RANGE_SCAN_ASC);

  range_key_part= table->key_info[active_index].key_part;

  if (!start_key)                       // Read first record
    result= ha_index_first(table->record[0]);
  else
    result= ha_index_read_map(table->record[0],
                              start_key->key,
                              start_key->keypart_map,
                              start_key->flag);
  if (result)
    DBUG_RETURN((result == HA_ERR_KEY_NOT_FOUND) 
                ? HA_ERR_END_OF_FILE
                : result);

  if (compare_key(end_range) <= 0)
  {
    DBUG_RETURN(0);
  }
  else
  {
    /*
      The last read row does not fall in the range. So request
      storage engine to release row lock if possible.
    */
    unlock_row();
    DBUG_RETURN(HA_ERR_END_OF_FILE);
  }
}


int handler::read_range_next()
{
  int result;
  DBUG_ENTER("handler::read_range_next");

  if (eq_range)
  {
    /* We trust that index_next_same always gives a row in range */
    DBUG_RETURN(ha_index_next_same(table->record[0],
                                   end_range->key,
                                   end_range->length));
  }
  result= ha_index_next(table->record[0]);
  if (result)
    DBUG_RETURN(result);

  if (compare_key(end_range) <= 0)
  {
    DBUG_RETURN(0);
  }
  else
  {
    /*
      The last read row does not fall in the range. So request
      storage engine to release row lock if possible.
    */
    unlock_row();
    DBUG_RETURN(HA_ERR_END_OF_FILE);
  }
}


void handler::set_end_range(const key_range* range,
                            enum_range_scan_direction direction)
{
  if (range)
  {
    save_end_range= *range;
    end_range= &save_end_range;
    range_key_part= table->key_info[active_index].key_part;
    key_compare_result_on_equal= ((range->flag == HA_READ_BEFORE_KEY) ? 1 :
                                  (range->flag == HA_READ_AFTER_KEY) ? -1 : 0);
  }
  else
    end_range= NULL;

  range_scan_direction= direction;
}


int handler::compare_key(key_range *range)
{
  int cmp;
  if (!range || in_range_check_pushed_down)
    return 0;                                   // No max range
  cmp= key_cmp(range_key_part, range->key, range->length);
  if (!cmp)
    cmp= key_compare_result_on_equal;
  return cmp;
}


/*
  Compare if a found key (in row) is within the range.

  This function is similar to compare_key() but checks the range scan
  direction to determine if this is a descending scan. This function
  is used by the index condition pushdown implementation to determine
  if the read record is within the range scan.

  @param range Range to compare to row. May be NULL for no range.

  @seealso
    handler::compare_key()

  @return Returns whether the key is within the range

    - 0   : Key is equal to range or 'range' == 0 (no range)
    - -1  : Key is within the current range
    - 1   : Key is outside the current range
*/

int handler::compare_key_icp(const key_range *range) const
{
  int cmp;
  if (!range)
    return 0;                                   // no max range
  cmp= key_cmp(range_key_part, range->key, range->length);
  if (!cmp)
    cmp= key_compare_result_on_equal;
  if (range_scan_direction == RANGE_SCAN_DESC)
    cmp= -cmp;
  return cmp;
}

int handler::index_read_idx_map(uchar * buf, uint index, const uchar * key,
                                key_part_map keypart_map,
                                enum ha_rkey_function find_flag)
{
  int error, error1;
  error= index_init(index, 0);
  if (!error)
  {
    error= index_read_map(buf, key, keypart_map, find_flag);
    error1= index_end();
  }
  return error ?  error : error1;
}


static my_bool exts_handlerton(THD *unused, plugin_ref plugin,
                               void *arg)
{
  List<char> *found_exts= (List<char> *) arg;
  handlerton *hton= plugin_data(plugin, handlerton *);
  handler *file;
  if (hton->state == SHOW_OPTION_YES && hton->create &&
      (file= hton->create(hton, (TABLE_SHARE*) 0, current_thd->mem_root)))
  {
    List_iterator_fast<char> it(*found_exts);
    const char **ext, *old_ext;

    for (ext= file->bas_ext(); *ext; ext++)
    {
      while ((old_ext= it++))
      {
        if (!strcmp(old_ext, *ext))
          break;
      }
      if (!old_ext)
        found_exts->push_back((char *) *ext);

      it.rewind();
    }
    delete file;
  }
  return FALSE;
}

TYPELIB* ha_known_exts()
{
  TYPELIB *known_extensions = (TYPELIB*) sql_alloc(sizeof(TYPELIB));
  known_extensions->name= "known_exts";
  known_extensions->type_lengths= NULL;
  
  List<char> found_exts;
  const char **ext, *old_ext;

  found_exts.push_back((char*) TRG_EXT);
  found_exts.push_back((char*) TRN_EXT);

  plugin_foreach(NULL, exts_handlerton,
                 MYSQL_STORAGE_ENGINE_PLUGIN, &found_exts);

  size_t arr_length= sizeof(char *)* (found_exts.elements+1);
  ext= (const char **) sql_alloc(arr_length);

  DBUG_ASSERT(NULL != ext);
  known_extensions->count= found_exts.elements;
  known_extensions->type_names= ext;

  List_iterator_fast<char> it(found_exts);
  while ((old_ext= it++))
    *ext++= old_ext;
  *ext= NULL;
  return known_extensions;
}


static bool stat_print(THD *thd, const char *type, uint type_len,
                       const char *file, uint file_len,
                       const char *status, uint status_len)
{
  Protocol *protocol= thd->protocol;
  protocol->prepare_for_resend();
  protocol->store(type, type_len, system_charset_info);
  protocol->store(file, file_len, system_charset_info);
  protocol->store(status, status_len, system_charset_info);
  if (protocol->write())
    return TRUE;
  return FALSE;
}


static my_bool showstat_handlerton(THD *thd, plugin_ref plugin,
                                   void *arg)
{
  enum ha_stat_type stat= *(enum ha_stat_type *) arg;
  handlerton *hton= plugin_data(plugin, handlerton *);
  if (hton->state == SHOW_OPTION_YES && hton->show_status &&
      hton->show_status(hton, thd, stat_print, stat))
    return TRUE;
  return FALSE;
}

bool ha_show_status(THD *thd, handlerton *db_type, enum ha_stat_type stat)
{
  List<Item> field_list;
  Protocol *protocol= thd->protocol;
  bool result;

  field_list.push_back(new Item_empty_string("Type",10));
  field_list.push_back(new Item_empty_string("Name",FN_REFLEN));
  field_list.push_back(new Item_empty_string("Status",10));

  if (protocol->send_result_set_metadata(&field_list,
                            Protocol::SEND_NUM_ROWS | Protocol::SEND_EOF))
    return TRUE;

  if (db_type == NULL)
  {
    result= plugin_foreach(thd, showstat_handlerton,
                           MYSQL_STORAGE_ENGINE_PLUGIN, &stat);
  }
  else
  {
    if (db_type->state != SHOW_OPTION_YES)
    {
      const LEX_STRING *name=&hton2plugin[db_type->slot]->name;
      result= stat_print(thd, name->str, name->length,
                         "", 0, "DISABLED", 8) ? 1 : 0;
    }
    else
      result= db_type->show_status &&
              db_type->show_status(db_type, thd, stat_print, stat) ? 1 : 0;
  }

  if (!result)
    my_eof(thd);
  return result;
}

/*
  Function to check if the conditions for row-based binlogging is
  correct for the table.

  A row in the given table should be replicated if:
  - Row-based replication is enabled in the current thread
  - The binlog is enabled
  - It is not a temporary table
  - The binary log is open
  - The database the table resides in shall be binlogged (binlog_*_db rules)
  - table is not mysql.event
*/

static bool check_table_binlog_row_based(THD *thd, TABLE *table)
{
  if (table->s->cached_row_logging_check == -1)
  {
    int const check(table->s->tmp_table == NO_TMP_TABLE &&
                    ! table->no_replicate &&
                    binlog_filter->db_ok(table->s->db.str));
    table->s->cached_row_logging_check= check;
  }

  DBUG_ASSERT(table->s->cached_row_logging_check == 0 ||
              table->s->cached_row_logging_check == 1);

  return (thd->is_current_stmt_binlog_format_row() &&
          table->s->cached_row_logging_check &&
          (thd->variables.option_bits & OPTION_BIN_LOG) &&
          mysql_bin_log.is_open());
}


static int write_locked_table_maps(THD *thd)
{
  DBUG_ENTER("write_locked_table_maps");
  DBUG_PRINT("enter", ("thd: 0x%lx  thd->lock: 0x%lx "
                       "thd->extra_lock: 0x%lx",
                       (long) thd, (long) thd->lock, (long) thd->extra_lock));

  DBUG_PRINT("debug", ("get_binlog_table_maps(): %d", thd->get_binlog_table_maps()));

  if (thd->get_binlog_table_maps() == 0)
  {
    MYSQL_LOCK *locks[2];
    locks[0]= thd->extra_lock;
    locks[1]= thd->lock;
    for (uint i= 0 ; i < sizeof(locks)/sizeof(*locks) ; ++i )
    {
      MYSQL_LOCK const *const lock= locks[i];
      if (lock == NULL)
        continue;

      bool need_binlog_rows_query= thd->variables.binlog_rows_query_log_events;
      TABLE **const end_ptr= lock->table + lock->table_count;
      for (TABLE **table_ptr= lock->table ; 
           table_ptr != end_ptr ;
           ++table_ptr)
      {
        TABLE *const table= *table_ptr;
        DBUG_PRINT("info", ("Checking table %s", table->s->table_name.str));
        if (table->current_lock == F_WRLCK &&
            check_table_binlog_row_based(thd, table))
        {
          /*
            We need to have a transactional behavior for SQLCOM_CREATE_TABLE
            (e.g. CREATE TABLE... SELECT * FROM TABLE) in order to keep a
            compatible behavior with the STMT based replication even when
            the table is not transactional. In other words, if the operation
            fails while executing the insert phase nothing is written to the
            binlog.

            Note that at this point, we check the type of a set of tables to
            create the table map events. In the function binlog_log_row(),
            which calls the current function, we check the type of the table
            of the current row.
          */
          bool const has_trans= thd->lex->sql_command == SQLCOM_CREATE_TABLE ||
                                table->file->has_transactions();
          int const error= thd->binlog_write_table_map(table, has_trans,
                                                       need_binlog_rows_query);
          /* Binlog Rows_query log event once for one statement which updates
             two or more tables.*/
          if (need_binlog_rows_query)
            need_binlog_rows_query= FALSE;
          /*
            If an error occurs, it is the responsibility of the caller to
            roll back the transaction.
          */
          if (unlikely(error))
            DBUG_RETURN(1);
        }
      }
    }
  }
  DBUG_RETURN(0);
}


typedef bool Log_func(THD*, TABLE*, bool,
                      const uchar*, const uchar*);

int binlog_log_row(TABLE* table,
                          const uchar *before_record,
                          const uchar *after_record,
                          Log_func *log_func)
{
  bool error= 0;
  THD *const thd= table->in_use;

  if (check_table_binlog_row_based(thd, table))
  {
    DBUG_DUMP("read_set 10", (uchar*) table->read_set->bitmap,
              (table->s->fields + 7) / 8);

    /*
      If there are no table maps written to the binary log, this is
      the first row handled in this statement. In that case, we need
      to write table maps for all locked tables to the binary log.
    */
    if (likely(!(error= write_locked_table_maps(thd))))
    {
      /*
        We need to have a transactional behavior for SQLCOM_CREATE_TABLE
        (i.e. CREATE TABLE... SELECT * FROM TABLE) in order to keep a
        compatible behavior with the STMT based replication even when
        the table is not transactional. In other words, if the operation
        fails while executing the insert phase nothing is written to the
        binlog.
      */
      bool const has_trans= thd->lex->sql_command == SQLCOM_CREATE_TABLE ||
                           table->file->has_transactions();
      error=
        (*log_func)(thd, table, has_trans, before_record, after_record);
    }
  }
  return error ? HA_ERR_RBR_LOGGING_FAILED : 0;
}

int handler::ha_external_lock(THD *thd, int lock_type)
{
  int error;
  DBUG_ENTER("handler::ha_external_lock");
  /*
    Whether this is lock or unlock, this should be true, and is to verify that
    if get_auto_increment() was called (thus may have reserved intervals or
    taken a table lock), ha_release_auto_increment() was too.
  */
  DBUG_ASSERT(next_insert_id == 0);
  /* Consecutive calls for lock without unlocking in between is not allowed */
  DBUG_ASSERT(table_share->tmp_table != NO_TMP_TABLE ||
              ((lock_type != F_UNLCK && m_lock_type == F_UNLCK) ||
               lock_type == F_UNLCK));
  /* SQL HANDLER call locks/unlock while scanning (RND/INDEX). */
  DBUG_ASSERT(inited == NONE || table->open_by_handler);

  if (MYSQL_HANDLER_RDLOCK_START_ENABLED() ||
      MYSQL_HANDLER_WRLOCK_START_ENABLED() ||
      MYSQL_HANDLER_UNLOCK_START_ENABLED())
  {
    if (lock_type == F_RDLCK)
    {
      MYSQL_HANDLER_RDLOCK_START(table_share->db.str,
                                 table_share->table_name.str);
    }
    else if (lock_type == F_WRLCK)
    {
      MYSQL_HANDLER_WRLOCK_START(table_share->db.str,
                                 table_share->table_name.str);
    }
    else if (lock_type == F_UNLCK)
    {
      MYSQL_HANDLER_UNLOCK_START(table_share->db.str,
                                 table_share->table_name.str);
    }
  }

  ha_statistic_increment(&SSV::ha_external_lock_count);

  MYSQL_TABLE_LOCK_WAIT(m_psi, PSI_TABLE_EXTERNAL_LOCK, lock_type,
    { error= external_lock(thd, lock_type); })

  /*
    We cache the table flags if the locking succeeded. Otherwise, we
    keep them as they were when they were fetched in ha_open().
  */

  if (error == 0)
  {
    /*
      The lock type is needed by MRR when creating a clone of this handler
      object.
    */
    m_lock_type= lock_type;
    cached_table_flags= table_flags();
  }

  if (MYSQL_HANDLER_RDLOCK_DONE_ENABLED() ||
      MYSQL_HANDLER_WRLOCK_DONE_ENABLED() ||
      MYSQL_HANDLER_UNLOCK_DONE_ENABLED())
  {
    if (lock_type == F_RDLCK)
    {
      MYSQL_HANDLER_RDLOCK_DONE(error);
    }
    else if (lock_type == F_WRLCK)
    {
      MYSQL_HANDLER_WRLOCK_DONE(error);
    }
    else if (lock_type == F_UNLCK)
    {
      MYSQL_HANDLER_UNLOCK_DONE(error);
    }
  }
  DBUG_RETURN(error);
}


int handler::ha_reset()
{
  DBUG_ENTER("handler::ha_reset");
  /* Check that we have called all proper deallocation functions */
  DBUG_ASSERT((uchar*) table->def_read_set.bitmap +
              table->s->column_bitmap_size ==
              (uchar*) table->def_write_set.bitmap);
  DBUG_ASSERT(bitmap_is_set_all(&table->s->all_set));
  DBUG_ASSERT(table->key_read == 0);
  /* ensure that ha_index_end / ha_rnd_end has been called */
  DBUG_ASSERT(inited == NONE);
  /* Free cache used by filesort */
  free_io_cache(table);
  /* reset the bitmaps to point to defaults */
  table->default_column_bitmaps();
  /* Reset information about pushed engine conditions */
  pushed_cond= NULL;
  /* Reset information about pushed index conditions */
  cancel_pushed_idx_cond();

  const int retval= reset();
  DBUG_RETURN(retval);
}


int handler::ha_write_row(uchar *buf)
{
  int error;
  Log_func *log_func= Write_rows_log_event::binlog_row_logging_function;
  DBUG_ASSERT(table_share->tmp_table != NO_TMP_TABLE ||
              m_lock_type == F_WRLCK);

  DBUG_ENTER("handler::ha_write_row");
  DBUG_EXECUTE_IF("inject_error_ha_write_row",
                  DBUG_RETURN(HA_ERR_INTERNAL_ERROR); );

  MYSQL_INSERT_ROW_START(table_share->db.str, table_share->table_name.str);
  mark_trx_read_write();

  MYSQL_TABLE_IO_WAIT(m_psi, PSI_TABLE_WRITE_ROW, MAX_KEY, 0,
    { error= write_row(buf); })

  MYSQL_INSERT_ROW_DONE(error);
  if (unlikely(error))
    DBUG_RETURN(error);

  if (unlikely(error= binlog_log_row(table, 0, buf, log_func)))
    DBUG_RETURN(error); /* purecov: inspected */

  DEBUG_SYNC_C("ha_write_row_end");
  DBUG_RETURN(0);
}


int handler::ha_update_row(const uchar *old_data, uchar *new_data)
{
  int error;
  DBUG_ASSERT(table_share->tmp_table != NO_TMP_TABLE ||
              m_lock_type == F_WRLCK);
  Log_func *log_func= Update_rows_log_event::binlog_row_logging_function;

  /*
    Some storage engines require that the new record is in record[0]
    (and the old record is in record[1]).
   */
  DBUG_ASSERT(new_data == table->record[0]);
  DBUG_ASSERT(old_data == table->record[1]);

  MYSQL_UPDATE_ROW_START(table_share->db.str, table_share->table_name.str);
  mark_trx_read_write();

  MYSQL_TABLE_IO_WAIT(m_psi, PSI_TABLE_UPDATE_ROW, active_index, 0,
    { error= update_row(old_data, new_data);})

  MYSQL_UPDATE_ROW_DONE(error);
  if (unlikely(error))
    return error;
  if (unlikely(error= binlog_log_row(table, old_data, new_data, log_func)))
    return error;
  return 0;
}

int handler::ha_delete_row(const uchar *buf)
{
  int error;
  DBUG_ASSERT(table_share->tmp_table != NO_TMP_TABLE ||
              m_lock_type == F_WRLCK);
  Log_func *log_func= Delete_rows_log_event::binlog_row_logging_function;
  /*
    Normally table->record[0] is used, but sometimes table->record[1] is used.
  */
  DBUG_ASSERT(buf == table->record[0] ||
              buf == table->record[1]);
  DBUG_EXECUTE_IF("inject_error_ha_delete_row",
                  return HA_ERR_INTERNAL_ERROR; );

  MYSQL_DELETE_ROW_START(table_share->db.str, table_share->table_name.str);
  mark_trx_read_write();

  MYSQL_TABLE_IO_WAIT(m_psi, PSI_TABLE_DELETE_ROW, active_index, 0,
    { error= delete_row(buf);})

  MYSQL_DELETE_ROW_DONE(error);
  if (unlikely(error))
    return error;
  if (unlikely(error= binlog_log_row(table, buf, 0, log_func)))
    return error;
  return 0;
}



void handler::use_hidden_primary_key()
{
  /* fallback to use all columns in the table to identify row */
  table->use_all_columns();
}


Handler_share *handler::get_ha_share_ptr()
{
  DBUG_ENTER("handler::get_ha_share_ptr");
  DBUG_ASSERT(ha_share && table_share);

#ifndef DBUG_OFF
  if (table_share->tmp_table == NO_TMP_TABLE)
    mysql_mutex_assert_owner(&table_share->LOCK_ha_data);
#endif

  DBUG_RETURN(*ha_share);
}


void handler::set_ha_share_ptr(Handler_share *arg_ha_share)
{
  DBUG_ENTER("handler::set_ha_share_ptr");
  DBUG_ASSERT(ha_share);
#ifndef DBUG_OFF
  if (table_share->tmp_table == NO_TMP_TABLE)
    mysql_mutex_assert_owner(&table_share->LOCK_ha_data);
#endif

  *ha_share= arg_ha_share;
  DBUG_VOID_RETURN;
}


void handler::lock_shared_ha_data()
{
  DBUG_ASSERT(table_share);
  if (table_share->tmp_table == NO_TMP_TABLE)
    mysql_mutex_lock(&table_share->LOCK_ha_data);
}


void handler::unlock_shared_ha_data()
{
  DBUG_ASSERT(table_share);
  if (table_share->tmp_table == NO_TMP_TABLE)
    mysql_mutex_unlock(&table_share->LOCK_ha_data);
}


void signal_log_not_needed(struct handlerton, char *log_file)
{
  DBUG_ENTER("signal_log_not_needed");
  DBUG_PRINT("enter", ("logfile '%s'", log_file));
  DBUG_VOID_RETURN;
}

#ifdef TRANS_LOG_MGM_EXAMPLE_CODE
/*
  Example of transaction log management functions based on assumption that logs
  placed into a directory
*/
#include <my_dir.h>
#include <my_sys.h>
int example_of_iterator_using_for_logs_cleanup(handlerton *hton)
{
  void *buffer;
  int res= 1;
  struct handler_iterator iterator;
  struct handler_log_file_data data;

  if (!hton->create_iterator)
    return 1; /* iterator creator is not supported */

  if ((*hton->create_iterator)(hton, HA_TRANSACTLOG_ITERATOR, &iterator) !=
      HA_ITERATOR_OK)
  {
    /* error during creation of log iterator or iterator is not supported */
    return 1;
  }
  while((*iterator.next)(&iterator, (void*)&data) == 0)
  {
    printf("%s\n", data.filename.str);
    if (data.status == HA_LOG_STATUS_FREE &&
        mysql_file_delete(INSTRUMENT_ME,
                          data.filename.str, MYF(MY_WME)))
      goto err;
  }
  res= 0;
err:
  (*iterator.destroy)(&iterator);
  return res;
}


/*
  Here we should get info from handler where it save logs but here is
  just example, so we use constant.
  IMHO FN_ROOTDIR ("/") is safe enough for example, because nobody has
  rights on it except root and it consist of directories only at lest for
  *nix (sorry, can't find windows-safe solution here, but it is only example).
*/
#define fl_dir FN_ROOTDIR


enum log_status fl_get_log_status(char *log)
{
  MY_STAT stat_buff;
  if (mysql_file_stat(INSTRUMENT_ME, log, &stat_buff, MYF(0)))
    return HA_LOG_STATUS_INUSE;
  return HA_LOG_STATUS_NOSUCHLOG;
}


struct fl_buff
{
  LEX_STRING *names;
  enum log_status *statuses;
  uint32 entries;
  uint32 current;
};


int fl_log_iterator_next(struct handler_iterator *iterator,
                          void *iterator_object)
{
  struct fl_buff *buff= (struct fl_buff *)iterator->buffer;
  struct handler_log_file_data *data=
    (struct handler_log_file_data *) iterator_object;
  if (buff->current >= buff->entries)
    return 1;
  data->filename= buff->names[buff->current];
  data->status= buff->statuses[buff->current];
  buff->current++;
  return 0;
}


void fl_log_iterator_destroy(struct handler_iterator *iterator)
{
  my_free(iterator->buffer);
}


enum handler_create_iterator_result
fl_log_iterator_buffer_init(struct handler_iterator *iterator)
{
  MY_DIR *dirp;
  struct fl_buff *buff;
  char *name_ptr;
  uchar *ptr;
  FILEINFO *file;
  uint32 i;

  /* to be able to make my_free without crash in case of error */
  iterator->buffer= 0;

  if (!(dirp = my_dir(fl_dir, MYF(0))))
  {
    return HA_ITERATOR_ERROR;
  }
  if ((ptr= (uchar*)my_malloc(ALIGN_SIZE(sizeof(fl_buff)) +
                             ((ALIGN_SIZE(sizeof(LEX_STRING)) +
                               sizeof(enum log_status) +
                               + FN_REFLEN + 1) *
                              (uint) dirp->number_off_files),
                             MYF(0))) == 0)
  {
    return HA_ITERATOR_ERROR;
  }
  buff= (struct fl_buff *)ptr;
  buff->entries= buff->current= 0;
  ptr= ptr + (ALIGN_SIZE(sizeof(fl_buff)));
  buff->names= (LEX_STRING*) (ptr);
  ptr= ptr + ((ALIGN_SIZE(sizeof(LEX_STRING)) *
               (uint) dirp->number_off_files));
  buff->statuses= (enum log_status *)(ptr);
  name_ptr= (char *)(ptr + (sizeof(enum log_status) *
                            (uint) dirp->number_off_files));
  for (i=0 ; i < (uint) dirp->number_off_files  ; i++)
  {
    enum log_status st;
    file= dirp->dir_entry + i;
    if ((file->name[0] == '.' &&
         ((file->name[1] == '.' && file->name[2] == '\0') ||
            file->name[1] == '\0')))
      continue;
    if ((st= fl_get_log_status(file->name)) == HA_LOG_STATUS_NOSUCHLOG)
      continue;
    name_ptr= strxnmov(buff->names[buff->entries].str= name_ptr,
                       FN_REFLEN, fl_dir, file->name, NullS);
    buff->names[buff->entries].length= (name_ptr -
                                        buff->names[buff->entries].str);
    buff->statuses[buff->entries]= st;
    buff->entries++;
  }

  iterator->buffer= buff;
  iterator->next= &fl_log_iterator_next;
  iterator->destroy= &fl_log_iterator_destroy;
  return HA_ITERATOR_OK;
}


/* An example of a iterator creator */
enum handler_create_iterator_result
fl_create_iterator(enum handler_iterator_type type,
                   struct handler_iterator *iterator)
{
  switch(type) {
  case HA_TRANSACTLOG_ITERATOR:
    return fl_log_iterator_buffer_init(iterator);
  default:
    return HA_ITERATOR_UNSUPPORTED;
  }
}
#endif /*TRANS_LOG_MGM_EXAMPLE_CODE*/