~drizzle-trunk/drizzle/development

/* Copyright (C) 2000 MySQL AB

   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 */

/*

  Delete of records and truncate of tables.

  Multi-table deletes were introduced by Monty and Sinisa

*/

#include <config.h>

#include <drizzled/sql_select.h>

#include <drizzled/error.h>

#include <drizzled/probes.h>

#include <drizzled/sql_parse.h>

#include <drizzled/sql_base.h>

#include <drizzled/lock.h>

#include <drizzled/probes.h>

#include <drizzled/optimizer/range.h>

#include <drizzled/records.h>

#include <drizzled/internal/iocache.h>

#include <drizzled/transaction_services.h>

#include <drizzled/filesort.h>

#include <drizzled/sql_lex.h>

#include <drizzled/diagnostics_area.h>

#include <drizzled/statistics_variables.h>

#include <drizzled/session/transactions.h>

namespace drizzled {

/**

  Implement DELETE SQL word.

  @note Like implementations of other DDL/DML in MySQL, this function

  relies on the caller to close the thread tables. This is done in the

  end of dispatch_command().

*/

bool delete_query(Session *session, TableList *table_list, COND *conds,

                  SQL_LIST *order, ha_rows limit, uint64_t,

                  bool reset_auto_increment)

{

  int		error;

  Table		*table;

  optimizer::SqlSelect *select= NULL;

  ReadRecord	info;

  bool          using_limit=limit != HA_POS_ERROR;

  ha_rows	deleted= 0;

  uint32_t usable_index= MAX_KEY;

  Select_Lex   *select_lex= &session->lex().select_lex;

  Session::killed_state_t killed_status= Session::NOT_KILLED;

  if (session->openTablesLock(table_list))

  {

    DRIZZLE_DELETE_DONE(1, 0);

    return true;

  }

  table= table_list->table;

  assert(table);

  session->set_proc_info("init");

  table->map=1;

  if (prepare_delete(session, table_list, &conds))

  {

    DRIZZLE_DELETE_DONE(1, 0);

    return true;

  }

  /* check ORDER BY even if it can be ignored */

  if (order && order->elements)

  {

    TableList   tables;

    List<Item>   fields;

    List<Item>   all_fields;

    tables.table = table;

    tables.alias = table_list->alias;

    select_lex->setup_ref_array(session, order->elements);

    if (setup_order(session, select_lex->ref_pointer_array, &tables, fields, all_fields, (Order*) order->first))

    {

      delete select;

      free_underlaid_joins(session, &session->lex().select_lex);

      DRIZZLE_DELETE_DONE(1, 0);

      return true;

    }

  }

  bool const_cond= not conds || conds->const_item();

  select_lex->no_error= session->lex().ignore;

  bool const_cond_result= const_cond && (!conds || conds->val_int());

  if (session->is_error())

  {

    /* Error evaluating val_int(). */

    return true;

  }

  /*

    Test if the user wants to delete all rows and deletion doesn't have

    any side-effects (because of triggers), so we can use optimized

    handler::delete_all_rows() method.

    We implement fast TRUNCATE for InnoDB even if triggers are

    present.  TRUNCATE ignores triggers.

    We can use delete_all_rows() if and only if:

    - We allow new functions (not using option --skip-new), and are

      not in safe mode (not using option --safe-mode)

    - There is no limit clause

    - The condition is constant

    - If there is a condition, then it it produces a non-zero value

    - If the current command is DELETE FROM with no where clause

      (i.e., not TRUNCATE) then:

      - We should not be binlogging this statement row-based, and

      - there should be no delete triggers associated with the table.

  */

  if (!using_limit && const_cond_result)

  {

    /* Update the table->cursor->stats.records number */

    table->cursor->info(HA_STATUS_VARIABLE | HA_STATUS_NO_LOCK);

    ha_rows const maybe_deleted= table->cursor->stats.records;

    if (!(error=table->cursor->ha_delete_all_rows()))

    {

      error= -1;				// ok

      deleted= maybe_deleted;

      goto cleanup;

    }

    if (error != HA_ERR_WRONG_COMMAND)

    {

      table->print_error(error,MYF(0));

      error=0;

      goto cleanup;

    }

    /* Handler didn't support fast delete; Delete rows one by one */

  }

  if (conds)

  {

    Item::cond_result result;

    conds= remove_eq_conds(session, conds, &result);

    if (result == Item::COND_FALSE)             // Impossible where

      limit= 0;

  }

  /* Update the table->cursor->stats.records number */

  table->cursor->info(HA_STATUS_VARIABLE | HA_STATUS_NO_LOCK);

  table->covering_keys.reset();

  table->quick_keys.reset();		// Can't use 'only index'

  select= optimizer::make_select(table, 0, 0, conds, 0, &error);

  if (error)

  {

    DRIZZLE_DELETE_DONE(1, 0);

    return true;

  }

  if ((select && select->check_quick(session, false, limit)) || !limit)

  {

    delete select;

    free_underlaid_joins(session, select_lex);

    session->row_count_func= 0;

    if (session->is_error())

      return true;

    DRIZZLE_DELETE_DONE(0, 0);

    /**

     * Resetting the Diagnostic area to prevent

     * lp bug# 439719

     */

    session->main_da().reset_diagnostics_area();

    session->my_ok((ha_rows) session->rowCount());

    /*

      We don't need to call reset_auto_increment in this case, because

      mysql_truncate always gives a NULL conds argument, hence we never

      get here.

    */

    return 0; // Nothing to delete

  }

  /* If running in safe sql mode, don't allow updates without keys */

  if (table->quick_keys.none())

  {

    session->server_status|=SERVER_QUERY_NO_INDEX_USED;

  }

  if (order && order->elements)

  {

    if ((!select || table->quick_keys.none()) && limit != HA_POS_ERROR)

      usable_index= optimizer::get_index_for_order(table, (Order*)(order->first), limit);

    if (usable_index == MAX_KEY)

    {

      FileSort filesort(*session);

      table->sort.io_cache= new internal::io_cache_st;

      uint32_t length= 0;

      SortField* sortorder= make_unireg_sortorder((Order*) order->first, &length, NULL);

      ha_rows examined_rows;

      if ((table->sort.found_records= filesort.run(table, sortorder, length, select, HA_POS_ERROR, 1, examined_rows)) == HA_POS_ERROR)

      {

        delete select;

        free_underlaid_joins(session, &session->lex().select_lex);

        DRIZZLE_DELETE_DONE(1, 0);

        return true;

      }

      /*

        Filesort has already found and selected the rows we want to delete,

        so we don't need the where clause

      */

      delete select;

      free_underlaid_joins(session, select_lex);

      select= 0;

    }

  }

  /* If quick select is used, initialize it before retrieving rows. */

  if (select && select->quick && select->quick->reset())

  {

    delete select;

    free_underlaid_joins(session, select_lex);

    DRIZZLE_DELETE_DONE(1, 0);

    return true;

  }

  if (usable_index==MAX_KEY)

  {

    if ((error= info.init_read_record(session,table,select,1,1)))

    {

      table->print_error(error, MYF(0));

      delete select;

      free_underlaid_joins(session, select_lex);

      return true;

    }

  }

  else

  {

    if ((error= info.init_read_record_idx(session, table, 1, usable_index)))

    {

      table->print_error(error, MYF(0));

      delete select;

      free_underlaid_joins(session, select_lex);

      return true;

    }

  }

  session->set_proc_info("updating");

  table->mark_columns_needed_for_delete();

  while (!(error=info.read_record(&info)) && !session->getKilled() &&

	 ! session->is_error())

  {

    // session->is_error() is tested to disallow delete row on error

    if (!(select && select->skip_record())&& ! session->is_error() )

    {

      if (!(error= table->cursor->deleteRecord(table->getInsertRecord())))

      {

	deleted++;

	if (!--limit && using_limit)

	{

	  error= -1;

	  break;

	}

      }

      else

      {

	table->print_error(error,MYF(0));

	/*

	  In < 4.0.14 we set the error number to 0 here, but that

	  was not sensible, because then MySQL would not roll back the

	  failed DELETE, and also wrote it to the binlog. For MyISAM

	  tables a DELETE probably never should fail (?), but for

	  InnoDB it can fail in a FOREIGN KEY error or an

	  out-of-tablespace error.

	*/

 	error= 1;

	break;

      }

    }

    else

      table->cursor->unlock_row();  // Row failed selection, release lock on it

  }

  killed_status= session->getKilled();

  if (killed_status != Session::NOT_KILLED || session->is_error())

    error= 1;					// Aborted

  session->set_proc_info("end");

  info.end_read_record();

cleanup:

  if (reset_auto_increment && (error < 0))

  {

    /*

      We're really doing a truncate and need to reset the table's

      auto-increment counter.

    */

    int error2= table->cursor->ha_reset_auto_increment(0);

    if (error2 && (error2 != HA_ERR_WRONG_COMMAND))

    {

      table->print_error(error2, MYF(0));

      error= 1;

    }

  }

  delete select;

  bool transactional_table= table->cursor->has_transactions();

  if (!transactional_table && deleted > 0)

    session->transaction.stmt.markModifiedNonTransData();

  /* See similar binlogging code in sql_update.cc, for comments */

  if ((error < 0) || session->transaction.stmt.hasModifiedNonTransData())

  {

    if (session->transaction.stmt.hasModifiedNonTransData())

      session->transaction.all.markModifiedNonTransData();

  }

  assert(transactional_table || !deleted || session->transaction.stmt.hasModifiedNonTransData());

  free_underlaid_joins(session, select_lex);

  DRIZZLE_DELETE_DONE((error >= 0 || session->is_error()), deleted);

  if (error < 0 || (session->lex().ignore && !session->is_fatal_error))

  {

    session->row_count_func= deleted;

    /**

     * Resetting the Diagnostic area to prevent

     * lp bug# 439719

     */

    session->main_da().reset_diagnostics_area();

    session->my_ok((ha_rows) session->rowCount());

  }

  session->status_var.deleted_row_count+= deleted;

  return (error >= 0 || session->is_error());

}

/*

  Prepare items in DELETE statement

  SYNOPSIS

    prepare_delete()

    session			- thread handler

    table_list		- global/local table list

    conds		- conditions

  RETURN VALUE

    false OK

    true  error

*/

int prepare_delete(Session *session, TableList *table_list, Item **conds)

{

  Select_Lex *select_lex= &session->lex().select_lex;

  session->lex().allow_sum_func= 0;

  if (setup_tables_and_check_access(session, &session->lex().select_lex.context, &select_lex->top_join_list, 

    table_list, &select_lex->leaf_tables, false) ||

      session->setup_conds(table_list, conds))

    return true;

  if (unique_table(table_list, table_list->next_global))

  {

    my_error(ER_UPDATE_TABLE_USED, MYF(0), table_list->alias);

    return true;

  }

  List<Item> all_fields;

  if (select_lex->inner_refs_list.size() && fix_inner_refs(session, all_fields, select_lex, select_lex->ref_pointer_array))

    return true;

  return false;

}

/***************************************************************************

  TRUNCATE Table

****************************************************************************/

/*

  Optimize delete of all rows by doing a full generate of the table

  This will work even if the .ISM and .ISD tables are destroyed

*/

bool truncate(Session& session, TableList *table_list)

{

  uint64_t save_options= session.options;

  table_list->lock_type= TL_WRITE;

  session.options&= ~(OPTION_BEGIN | OPTION_NOT_AUTOCOMMIT);

  init_select(&session.lex());

  int error= delete_query(&session, table_list, (COND*) 0, (SQL_LIST*) 0, HA_POS_ERROR, 0L, true);

  /*

    Safety, in case the engine ignored ha_enable_transaction(false)

    above. Also clears session->transaction.*.

  */

  error= TransactionServices::autocommitOrRollback(session, error);

  session.options= save_options;

  return error;

}

} /* namespace drizzled */