sql_partition_admin.cc

/* Copyright (c) 2010, 2012, Oracle and/or its affiliates. All rights reserved.

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

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

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

#include "sql_parse.h"                      // check_access,
                                            // check_merge_table_access
                                            // check_one_table_access
#include "sql_table.h"                      // mysql_alter_table, etc.
#include "sql_cmd.h"                        // Sql_cmd
#include "sql_alter.h"                      // Sql_cmd_alter_table
#include "sql_partition.h"                  // struct partition_info, etc.
#include "sql_base.h"                       // open_and_lock_tables, etc
#include "debug_sync.h"                     // DEBUG_SYNC
#include "sql_truncate.h"                   // mysql_truncate_table,
                                            // Sql_cmd_truncate_table
#include "sql_admin.h"                      // Sql_cmd_Analyze/Check/.._table
#include "sql_partition_admin.h"            // Alter_table_*_partition
#ifdef WITH_PARTITION_STORAGE_ENGINE
#include "ha_partition.h"                   // ha_partition
#endif
#include "sql_base.h"                       // open_and_lock_tables

#ifndef WITH_PARTITION_STORAGE_ENGINE

bool Sql_cmd_partition_unsupported::execute(THD *)
{
  DBUG_ENTER("Sql_cmd_partition_unsupported::execute");
  /* error, partitioning support not compiled in... */
  my_error(ER_FEATURE_DISABLED, MYF(0), "partitioning",
           "--with-plugin-partition");
  DBUG_RETURN(TRUE);
}

#else

bool Sql_cmd_alter_table_exchange_partition::execute(THD *thd)
{
  /* Moved from mysql_execute_command */
  LEX *lex= thd->lex;
  /* first SELECT_LEX (have special meaning for many of non-SELECTcommands) */
  SELECT_LEX *select_lex= &lex->select_lex;
  /* first table of first SELECT_LEX */
  TABLE_LIST *first_table= (TABLE_LIST*) select_lex->table_list.first;
  /*
    Code in mysql_alter_table() may modify its HA_CREATE_INFO argument,
    so we have to use a copy of this structure to make execution
    prepared statement- safe. A shallow copy is enough as no memory
    referenced from this structure will be modified.
    @todo move these into constructor...
  */
  HA_CREATE_INFO create_info(lex->create_info);
  Alter_info alter_info(lex->alter_info, thd->mem_root);
  ulong priv_needed= ALTER_ACL | DROP_ACL | INSERT_ACL | CREATE_ACL;

  DBUG_ENTER("Sql_cmd_alter_table_exchange_partition::execute");

  if (thd->is_fatal_error) /* out of memory creating a copy of alter_info */
    DBUG_RETURN(TRUE);

  /* Must be set in the parser */
  DBUG_ASSERT(select_lex->db);
  /* also check the table to be exchanged with the partition */
  DBUG_ASSERT(alter_info.flags & Alter_info::ALTER_EXCHANGE_PARTITION);

  if (check_access(thd, priv_needed, first_table->db,
                   &first_table->grant.privilege,
                   &first_table->grant.m_internal,
                   0, 0) ||
      check_access(thd, priv_needed, first_table->next_local->db,
                   &first_table->next_local->grant.privilege,
                   &first_table->next_local->grant.m_internal,
                   0, 0))
    DBUG_RETURN(TRUE);

  if (check_grant(thd, priv_needed, first_table, FALSE, UINT_MAX, FALSE))
    DBUG_RETURN(TRUE);

  /* Not allowed with EXCHANGE PARTITION */
  DBUG_ASSERT(!create_info.data_file_name && !create_info.index_file_name);

  thd->enable_slow_log= opt_log_slow_admin_statements;
  DBUG_RETURN(exchange_partition(thd, first_table, &alter_info));
}


static bool check_exchange_partition(TABLE *table, TABLE *part_table)
{
  DBUG_ENTER("check_exchange_partition");

  /* Both tables must exist */
  if (!part_table || !table)
  {
    my_error(ER_CHECK_NO_SUCH_TABLE, MYF(0));
    DBUG_RETURN(TRUE);
  }

  /* The first table must be partitioned, and the second must not */
  if (!part_table->part_info)
  {
    my_error(ER_PARTITION_MGMT_ON_NONPARTITIONED, MYF(0));
    DBUG_RETURN(TRUE);
  }
  if (table->part_info)
  {
    my_error(ER_PARTITION_EXCHANGE_PART_TABLE, MYF(0),
             table->s->table_name.str);
    DBUG_RETURN(TRUE);
  }

  if (part_table->file->ht != partition_hton)
  {
    /*
      Only allowed on partitioned tables throught the generic ha_partition
      handler, i.e not yet for native partitioning (NDB).
    */
    my_error(ER_PARTITION_MGMT_ON_NONPARTITIONED, MYF(0));
    DBUG_RETURN(TRUE);
  }

  if (table->file->ht != part_table->part_info->default_engine_type)
  {
    my_error(ER_MIX_HANDLER_ERROR, MYF(0));
    DBUG_RETURN(TRUE);
  }

  /* Verify that table is not tmp table, partitioned tables cannot be tmp. */
  if (table->s->tmp_table != NO_TMP_TABLE)
  {
    my_error(ER_PARTITION_EXCHANGE_TEMP_TABLE, MYF(0),
             table->s->table_name.str);
    DBUG_RETURN(TRUE);
  }

  /* The table cannot have foreign keys constraints or be referenced */
  if(!table->file->can_switch_engines())
  {
    my_error(ER_PARTITION_EXCHANGE_FOREIGN_KEY, MYF(0),
             table->s->table_name.str);
    DBUG_RETURN(TRUE);
  }
  DBUG_RETURN(FALSE);
}


static bool compare_table_with_partition(THD *thd, TABLE *table,
                                         TABLE *part_table,
                                         partition_element *part_elem)
{
  HA_CREATE_INFO table_create_info, part_create_info;
  Alter_info part_alter_info;
  Alter_table_ctx part_alter_ctx; // Not used
  DBUG_ENTER("compare_table_with_partition");

  bool metadata_equal= false;
  memset(&part_create_info, 0, sizeof(HA_CREATE_INFO));
  memset(&table_create_info, 0, sizeof(HA_CREATE_INFO));

  update_create_info_from_table(&table_create_info, table);
  /* get the current auto_increment value */
  table->file->update_create_info(&table_create_info);
  /* mark all columns used, since they are used when preparing the new table */
  part_table->use_all_columns();
  table->use_all_columns();
  if (mysql_prepare_alter_table(thd, part_table, &part_create_info,
                                &part_alter_info, &part_alter_ctx))
  {
    my_error(ER_TABLES_DIFFERENT_METADATA, MYF(0));
    DBUG_RETURN(TRUE);
  }
  /* db_type is not set in prepare_alter_table */
  part_create_info.db_type= part_table->part_info->default_engine_type;
  /*
    Since we exchange the partition with the table, allow exchanging
    auto_increment value as well.
  */
  part_create_info.auto_increment_value=
                                table_create_info.auto_increment_value;

  /* Check compatible row_types and set create_info accordingly. */
  {
    enum row_type part_row_type= part_table->file->get_row_type();
    enum row_type table_row_type= table->file->get_row_type();
    if (part_row_type != table_row_type)
    {
      my_error(ER_PARTITION_EXCHANGE_DIFFERENT_OPTION, MYF(0),
               "ROW_FORMAT");
      DBUG_RETURN(true);
    }
    part_create_info.row_type= table->s->row_type;
  }

  /*
    NOTE: ha_blackhole does not support check_if_compatible_data,
    so this always fail for blackhole tables.
    ha_myisam compares pointers to verify that DATA/INDEX DIRECTORY is
    the same, so any table using data/index_file_name will fail.
  */
  if (mysql_compare_tables(table, &part_alter_info, &part_create_info,
                           &metadata_equal))
  {
    my_error(ER_TABLES_DIFFERENT_METADATA, MYF(0));
    DBUG_RETURN(TRUE);
  }

  DEBUG_SYNC(thd, "swap_partition_after_compare_tables");
  if (!metadata_equal)
  {
    my_error(ER_TABLES_DIFFERENT_METADATA, MYF(0));
    DBUG_RETURN(TRUE);
  }
  DBUG_ASSERT(table->s->db_create_options ==
              part_table->s->db_create_options);
  DBUG_ASSERT(table->s->db_options_in_use ==
              part_table->s->db_options_in_use);

  if (table_create_info.avg_row_length != part_create_info.avg_row_length)
  {
    my_error(ER_PARTITION_EXCHANGE_DIFFERENT_OPTION, MYF(0),
             "AVG_ROW_LENGTH");
    DBUG_RETURN(TRUE);
  }

  if (table_create_info.table_options != part_create_info.table_options)
  {
    my_error(ER_PARTITION_EXCHANGE_DIFFERENT_OPTION, MYF(0),
             "TABLE OPTION");
    DBUG_RETURN(TRUE);
  }

  if (table->s->table_charset != part_table->s->table_charset)
  {
    my_error(ER_PARTITION_EXCHANGE_DIFFERENT_OPTION, MYF(0),
             "CHARACTER SET");
    DBUG_RETURN(TRUE);
  }

  /*
    NOTE: We do not support update of frm-file, i.e. change
    max/min_rows, data/index_file_name etc.
    The workaround is to use REORGANIZE PARTITION to rewrite
    the frm file and then use EXCHANGE PARTITION when they are the same.
  */
  if (compare_partition_options(&table_create_info, part_elem))
    DBUG_RETURN(TRUE);

  DBUG_RETURN(FALSE);
}


static bool exchange_name_with_ddl_log(THD *thd,
                                       const char *name,
                                       const char *from_name,
                                       const char *tmp_name,
                                       handlerton *ht)
{
  DDL_LOG_ENTRY exchange_entry;
  DDL_LOG_MEMORY_ENTRY *log_entry= NULL;
  DDL_LOG_MEMORY_ENTRY *exec_log_entry= NULL;
  bool error= TRUE;
  bool error_set= FALSE;
  handler *file= NULL;
  DBUG_ENTER("exchange_name_with_ddl_log");

  if (!(file= get_new_handler(NULL, thd->mem_root, ht)))
  {
    mem_alloc_error(sizeof(handler));
    DBUG_RETURN(TRUE);
  }

  /* prepare the action entry */
  exchange_entry.entry_type=   DDL_LOG_ENTRY_CODE;
  exchange_entry.action_type=  DDL_LOG_EXCHANGE_ACTION;
  exchange_entry.next_entry=   0;
  exchange_entry.name=         name;
  exchange_entry.from_name=    from_name;
  exchange_entry.tmp_name=     tmp_name;
  exchange_entry.handler_name= ha_resolve_storage_engine_name(ht);
  exchange_entry.phase=        EXCH_PHASE_NAME_TO_TEMP;

  mysql_mutex_lock(&LOCK_gdl);
  /*
    write to the ddl log what to do by:
    1) write the action entry (i.e. which names to be exchanged)
    2) write the execution entry with a link to the action entry
  */
  DBUG_EXECUTE_IF("exchange_partition_fail_1", goto err_no_action_written;);
  DBUG_EXECUTE_IF("exchange_partition_abort_1", DBUG_SUICIDE(););
  if (write_ddl_log_entry(&exchange_entry, &log_entry))
    goto err_no_action_written;

  DBUG_EXECUTE_IF("exchange_partition_fail_2", goto err_no_execute_written;);
  DBUG_EXECUTE_IF("exchange_partition_abort_2", DBUG_SUICIDE(););
  if (write_execute_ddl_log_entry(log_entry->entry_pos, FALSE, &exec_log_entry))
    goto err_no_execute_written;
  /* ddl_log is written and synced */

  mysql_mutex_unlock(&LOCK_gdl);
  /*
    Execute the name exchange.
    Do one rename, increase the phase, update the action entry and sync.
    In case of errors in the ddl_log we must fail and let the ddl_log try
    to revert the changes, since otherwise it could revert the command after
    we sent OK to the client.
  */
  /* call rename table from table to tmp-name */
  DBUG_EXECUTE_IF("exchange_partition_fail_3",
                  my_error(ER_ERROR_ON_RENAME, MYF(0),
                           name, tmp_name, 0, "n/a");
                  error_set= TRUE;
                  goto err_rename;);
  DBUG_EXECUTE_IF("exchange_partition_abort_3", DBUG_SUICIDE(););
  if (file->ha_rename_table(name, tmp_name))
  {
    char errbuf[MYSYS_STRERROR_SIZE];
    my_error(ER_ERROR_ON_RENAME, MYF(0), name, tmp_name,
             my_errno, my_strerror(errbuf, sizeof(errbuf), my_errno));
    error_set= TRUE;
    goto err_rename;
  }
  DBUG_EXECUTE_IF("exchange_partition_fail_4", goto err_rename;);
  DBUG_EXECUTE_IF("exchange_partition_abort_4", DBUG_SUICIDE(););
  if (deactivate_ddl_log_entry(log_entry->entry_pos))
    goto err_rename;

  /* call rename table from partition to table */
  DBUG_EXECUTE_IF("exchange_partition_fail_5",
                  my_error(ER_ERROR_ON_RENAME, MYF(0),
                           from_name, name, 0, "n/a");
                  error_set= TRUE;
                  goto err_rename;);
  DBUG_EXECUTE_IF("exchange_partition_abort_5", DBUG_SUICIDE(););
  if (file->ha_rename_table(from_name, name))
  {
    char errbuf[MYSYS_STRERROR_SIZE];
    my_error(ER_ERROR_ON_RENAME, MYF(0), from_name, name,
             my_errno, my_strerror(errbuf, sizeof(errbuf), my_errno));
    error_set= TRUE;
    goto err_rename;
  }
  DBUG_EXECUTE_IF("exchange_partition_fail_6", goto err_rename;);
  DBUG_EXECUTE_IF("exchange_partition_abort_6", DBUG_SUICIDE(););
  if (deactivate_ddl_log_entry(log_entry->entry_pos))
    goto err_rename;

  /* call rename table from tmp-nam to partition */
  DBUG_EXECUTE_IF("exchange_partition_fail_7",
                  my_error(ER_ERROR_ON_RENAME, MYF(0),
                           tmp_name, from_name, 0, "n/a");
                  error_set= TRUE;
                  goto err_rename;);
  DBUG_EXECUTE_IF("exchange_partition_abort_7", DBUG_SUICIDE(););
  if (file->ha_rename_table(tmp_name, from_name))
  {
    char errbuf[MYSYS_STRERROR_SIZE];
    my_error(ER_ERROR_ON_RENAME, MYF(0), tmp_name, from_name,
             my_errno, my_strerror(errbuf, sizeof(errbuf), my_errno));
    error_set= TRUE;
    goto err_rename;
  }
  DBUG_EXECUTE_IF("exchange_partition_fail_8", goto err_rename;);
  DBUG_EXECUTE_IF("exchange_partition_abort_8", DBUG_SUICIDE(););
  if (deactivate_ddl_log_entry(log_entry->entry_pos))
    goto err_rename;

  /* The exchange is complete and ddl_log is deactivated */
  DBUG_EXECUTE_IF("exchange_partition_fail_9", goto err_rename;);
  DBUG_EXECUTE_IF("exchange_partition_abort_9", DBUG_SUICIDE(););
  /* all OK */
  error= FALSE;
  delete file;
  DBUG_RETURN(error);
err_rename:
  /*
    Nothing to do if any of these commands fails :( the commands itselfs
    will log to the error log about the failures...
  */
  /* execute the ddl log entry to revert the renames */
  (void) execute_ddl_log_entry(current_thd, log_entry->entry_pos);
  mysql_mutex_lock(&LOCK_gdl);
  /* mark the execute log entry done */
  (void) write_execute_ddl_log_entry(0, TRUE, &exec_log_entry);
  /* release the execute log entry */
  (void) release_ddl_log_memory_entry(exec_log_entry);
err_no_execute_written:
  /* release the action log entry */
  (void) release_ddl_log_memory_entry(log_entry);
err_no_action_written:
  mysql_mutex_unlock(&LOCK_gdl);
  delete file;
  if (!error_set)
    my_error(ER_DDL_LOG_ERROR, MYF(0));
  DBUG_RETURN(error);
}


bool Sql_cmd_alter_table_exchange_partition::
  exchange_partition(THD *thd, TABLE_LIST *table_list, Alter_info *alter_info)
{
  TABLE *part_table, *swap_table;
  TABLE_LIST *swap_table_list;
  handlerton *table_hton;
  partition_element *part_elem;
  char *partition_name;
  char temp_name[FN_REFLEN+1];
  char part_file_name[FN_REFLEN+1];
  char swap_file_name[FN_REFLEN+1];
  char temp_file_name[FN_REFLEN+1];
  uint swap_part_id;
  uint part_file_name_len;
  Alter_table_prelocking_strategy alter_prelocking_strategy;
  MDL_ticket *swap_table_mdl_ticket= NULL;
  MDL_ticket *part_table_mdl_ticket= NULL;
  uint table_counter;
  bool error= TRUE;
  DBUG_ENTER("mysql_exchange_partition");
  DBUG_ASSERT(alter_info->flags & Alter_info::ALTER_EXCHANGE_PARTITION);

  /* Don't allow to exchange with log table */
  swap_table_list= table_list->next_local;
  if (check_if_log_table(swap_table_list->db_length, swap_table_list->db,
                         swap_table_list->table_name_length,
                         swap_table_list->table_name, 0))
  {
    my_error(ER_WRONG_USAGE, MYF(0), "PARTITION", "log table");
    DBUG_RETURN(TRUE);
  }

  /*
    Currently no MDL lock that allows both read and write and is upgradeable
    to exclusive, so leave the lock type to TL_WRITE_ALLOW_READ also on the
    partitioned table.

    TODO: add MDL lock that allows both read and write and is upgradable to
    exclusive lock. This would allow to continue using the partitioned table
    also with update/insert/delete while the verification of the swap table
    is running.
  */

  /*
    NOTE: It is not possible to exchange a crashed partition/table since
    we need some info from the engine, which we can only access after open,
    to be able to verify the structure/metadata.
  */
  table_list->mdl_request.set_type(MDL_SHARED_NO_WRITE);
  if (open_tables(thd, &table_list, &table_counter, 0,
                  &alter_prelocking_strategy))
    DBUG_RETURN(true);

  part_table= table_list->table;
  swap_table= swap_table_list->table;

  if (check_exchange_partition(swap_table, part_table))
    DBUG_RETURN(TRUE);

  /* set lock pruning on first table */
  partition_name= alter_info->partition_names.head();
  if (table_list->table->part_info->
        set_named_partition_bitmap(partition_name, strlen(partition_name)))
    DBUG_RETURN(true);

  if (lock_tables(thd, table_list, table_counter, 0))
    DBUG_RETURN(true);


  table_hton= swap_table->file->ht;

  THD_STAGE_INFO(thd, stage_verifying_table);

  /* Will append the partition name later in part_info->get_part_elem() */
  part_file_name_len= build_table_filename(part_file_name,
                                           sizeof(part_file_name),
                                           table_list->db,
                                           table_list->table_name,
                                           "", 0);
  build_table_filename(swap_file_name,
                       sizeof(swap_file_name),
                       swap_table_list->db,
                       swap_table_list->table_name,
                       "", 0);
  /* create a unique temp name #sqlx-nnnn_nnnn, x for eXchange */
  my_snprintf(temp_name, sizeof(temp_name), "%sx-%lx_%lx",
              tmp_file_prefix, current_pid, thd->thread_id);
  if (lower_case_table_names)
    my_casedn_str(files_charset_info, temp_name);
  build_table_filename(temp_file_name, sizeof(temp_file_name),
                       table_list->next_local->db,
                       temp_name, "", FN_IS_TMP);

  if (!(part_elem= part_table->part_info->get_part_elem(partition_name,
                                                        part_file_name +
                                                          part_file_name_len,
                                                        &swap_part_id)))
  {
    my_error(ER_UNKNOWN_PARTITION, MYF(0), partition_name,
             part_table->alias);
    DBUG_RETURN(TRUE);
  }

  if (swap_part_id == NOT_A_PARTITION_ID)
  {
    DBUG_ASSERT(part_table->part_info->is_sub_partitioned());
    my_error(ER_PARTITION_INSTEAD_OF_SUBPARTITION, MYF(0));
    DBUG_RETURN(TRUE);
  }

  if (compare_table_with_partition(thd, swap_table, part_table, part_elem))
    DBUG_RETURN(TRUE);

  /* Table and partition has same structure/options, OK to exchange */

  thd_proc_info(thd, "verifying data with partition");

  if (verify_data_with_partition(swap_table, part_table, swap_part_id))
    DBUG_RETURN(TRUE);

  /*
    Get exclusive mdl lock on both tables, alway the non partitioned table
    first. Remember the tickets for downgrading locks later.
  */
  swap_table_mdl_ticket= swap_table->mdl_ticket;
  part_table_mdl_ticket= part_table->mdl_ticket;

  /*
    No need to set used_partitions to only propagate
    HA_EXTRA_PREPARE_FOR_RENAME to one part since no built in engine uses
    that flag. And the action would probably be to force close all other
    instances which is what we are doing any way.
  */
  if (wait_while_table_is_used(thd, swap_table, HA_EXTRA_PREPARE_FOR_RENAME) ||
      wait_while_table_is_used(thd, part_table, HA_EXTRA_PREPARE_FOR_RENAME))
    goto err;

  DEBUG_SYNC(thd, "swap_partition_after_wait");

  close_all_tables_for_name(thd, swap_table->s, false, NULL);
  close_all_tables_for_name(thd, part_table->s, false, NULL);

  DEBUG_SYNC(thd, "swap_partition_before_rename");

  if (exchange_name_with_ddl_log(thd, swap_file_name, part_file_name,
                                 temp_file_name, table_hton))
    goto err;

  /*
    Reopen tables under LOCK TABLES. Ignore the return value for now. It's
    better to keep master/slave in consistent state. Alternative would be to
    try to revert the exchange operation and issue error.
  */
  (void) thd->locked_tables_list.reopen_tables(thd);

  if ((error= write_bin_log(thd, TRUE, thd->query(), thd->query_length())))
  {
    /*
      The error is reported in write_bin_log().
      We try to revert to make it easier to keep the master/slave in sync.
    */
    (void) exchange_name_with_ddl_log(thd, part_file_name, swap_file_name,
                                      temp_file_name, table_hton);
  }

err:
  if (thd->locked_tables_mode)
  {
    if (swap_table_mdl_ticket)
      swap_table_mdl_ticket->downgrade_lock(MDL_SHARED_NO_READ_WRITE);
    if (part_table_mdl_ticket)
      part_table_mdl_ticket->downgrade_lock(MDL_SHARED_NO_READ_WRITE);
  }

  if (!error)
    my_ok(thd);

  // For query cache
  table_list->table= NULL;
  table_list->next_local->table= NULL;
  query_cache_invalidate3(thd, table_list, FALSE);

  DBUG_RETURN(error);
}


bool Sql_cmd_alter_table_analyze_partition::execute(THD *thd)
{
  bool res;
  DBUG_ENTER("Sql_cmd_alter_table_analyze_partition::execute");

  /*
    Flag that it is an ALTER command which administrates partitions, used
    by ha_partition
  */
  thd->lex->alter_info.flags|= Alter_info::ALTER_ADMIN_PARTITION;

  res= Sql_cmd_analyze_table::execute(thd);
    
  DBUG_RETURN(res);
}


bool Sql_cmd_alter_table_check_partition::execute(THD *thd)
{
  bool res;
  DBUG_ENTER("Sql_cmd_alter_table_check_partition::execute");

  /*
    Flag that it is an ALTER command which administrates partitions, used
    by ha_partition
  */
  thd->lex->alter_info.flags|= Alter_info::ALTER_ADMIN_PARTITION;

  res= Sql_cmd_check_table::execute(thd);

  DBUG_RETURN(res);
}


bool Sql_cmd_alter_table_optimize_partition::execute(THD *thd)
{
  bool res;
  DBUG_ENTER("Alter_table_optimize_partition_statement::execute");

  /*
    Flag that it is an ALTER command which administrates partitions, used
    by ha_partition
  */
  thd->lex->alter_info.flags|= Alter_info::ALTER_ADMIN_PARTITION;

  res= Sql_cmd_optimize_table::execute(thd);

  DBUG_RETURN(res);
}


bool Sql_cmd_alter_table_repair_partition::execute(THD *thd)
{
  bool res;
  DBUG_ENTER("Sql_cmd_alter_table_repair_partition::execute");

  /*
    Flag that it is an ALTER command which administrates partitions, used
    by ha_partition
  */
  thd->lex->alter_info.flags|= Alter_info::ALTER_ADMIN_PARTITION;

  res= Sql_cmd_repair_table::execute(thd);

  DBUG_RETURN(res);
}


bool Sql_cmd_alter_table_truncate_partition::execute(THD *thd)
{
  int error;
  ha_partition *partition;
  ulong timeout= thd->variables.lock_wait_timeout;
  TABLE_LIST *first_table= thd->lex->select_lex.table_list.first;
  Alter_info *alter_info= &thd->lex->alter_info;
  uint table_counter, i;
  List<String> partition_names_list;
  bool binlog_stmt;
  DBUG_ENTER("Sql_cmd_alter_table_truncate_partition::execute");

  /*
    Flag that it is an ALTER command which administrates partitions, used
    by ha_partition.
  */
  thd->lex->alter_info.flags|= Alter_info::ALTER_ADMIN_PARTITION |
                               Alter_info::ALTER_TRUNCATE_PARTITION;

  /* Fix the lock types (not the same as ordinary ALTER TABLE). */
  first_table->lock_type= TL_WRITE;
  first_table->mdl_request.set_type(MDL_EXCLUSIVE);

  /*
    Check table permissions and open it with a exclusive lock.
    Ensure it is a partitioned table and finally, upcast the
    handler and invoke the partition truncate method. Lastly,
    write the statement to the binary log if necessary.
  */

  if (check_one_table_access(thd, DROP_ACL, first_table))
    DBUG_RETURN(TRUE);

  if (open_tables(thd, &first_table, &table_counter, 0))
    DBUG_RETURN(true);

  /*
    TODO: Add support for TRUNCATE PARTITION for NDB and other
          engines supporting native partitioning.
  */

  if (!first_table->table || first_table->view ||
      first_table->table->s->db_type() != partition_hton)
  {
    my_error(ER_PARTITION_MGMT_ON_NONPARTITIONED, MYF(0));
    DBUG_RETURN(TRUE);
  }

  
  /*
    Prune all, but named partitions,
    to avoid excessive calls to external_lock().
  */
  List_iterator<char> partition_names_it(alter_info->partition_names);
  uint num_names= alter_info->partition_names.elements;
  for (i= 0; i < num_names; i++)
  {
    char *partition_name= partition_names_it++;
    String *str_partition_name= new (thd->mem_root)
                                  String(partition_name, system_charset_info);
    if (!str_partition_name)
      DBUG_RETURN(true);
    partition_names_list.push_back(str_partition_name);
  }
  first_table->partition_names= &partition_names_list;
  if (first_table->table->part_info->set_partition_bitmaps(first_table))
    DBUG_RETURN(true);

  if (lock_tables(thd, first_table, table_counter, 0))
    DBUG_RETURN(true);

  /*
    Under locked table modes this might still not be an exclusive
    lock. Hence, upgrade the lock since the handler truncate method
    mandates an exclusive metadata lock.
  */
  MDL_ticket *ticket= first_table->table->mdl_ticket;
  if (thd->mdl_context.upgrade_shared_lock(ticket, MDL_EXCLUSIVE, timeout))
    DBUG_RETURN(TRUE);

  tdc_remove_table(thd, TDC_RT_REMOVE_NOT_OWN, first_table->db,
                   first_table->table_name, FALSE);

  partition= (ha_partition*) first_table->table->file;
  /* Invoke the handler method responsible for truncating the partition. */
  if ((error= partition->truncate_partition(alter_info, &binlog_stmt)))
    partition->print_error(error, MYF(0));

  /*
    All effects of a truncate operation are committed even if the
    operation fails. Thus, the query must be written to the binary
    log. The exception is a unimplemented truncate method or failure
    before any call to handler::truncate() is done.
    Also, it is logged in statement format, regardless of the binlog format.
  */
  if (error != HA_ERR_WRONG_COMMAND && binlog_stmt)
    error|= write_bin_log(thd, !error, thd->query(), thd->query_length());

  /*
    A locked table ticket was upgraded to a exclusive lock. After the
    the query has been written to the binary log, downgrade the lock
    to a shared one.
  */
  if (thd->locked_tables_mode)
    ticket->downgrade_lock(MDL_SHARED_NO_READ_WRITE);

  if (! error)
    my_ok(thd);

  // Invalidate query cache
  DBUG_ASSERT(!first_table->next_local);
  query_cache_invalidate3(thd, first_table, FALSE);

  DBUG_RETURN(error);
}

#endif /* WITH_PARTITION_STORAGE_ENGINE */