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BUG#12915: Added single-table UPDATE/DELTE ... ORDER BY ... LIMIT

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optimization: now can use index to find records to update/delete
when there is no WHERE clause.
This commit is contained in:
sergefp@mysql.com
2005-09-30 15:21:37 +04:00
parent bd417d158e
commit e9f2f9437a
9 changed files with 343 additions and 23 deletions
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48
sql/sql_delete.cc
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@@ -37,6 +37,7 @@ int mysql_delete(THD *thd, TABLE_LIST *table_list, COND *conds,
bool using_limit=limit != HA_POS_ERROR;
bool transactional_table, log_delayed, safe_update, const_cond;
ha_rows deleted;
uint usable_index= MAX_KEY;
DBUG_ENTER("mysql_delete");
if ((open_and_lock_tables(thd, table_list)))
@@ -119,30 +120,47 @@ int mysql_delete(THD *thd, TABLE_LIST *table_list, COND *conds,
tables.table = table;
tables.alias = table_list->alias;
table->sort.io_cache = (IO_CACHE *) my_malloc(sizeof(IO_CACHE),
MYF(MY_FAE | MY_ZEROFILL));
if (thd->lex->select_lex.setup_ref_array(thd, order->elements) ||
setup_order(thd, thd->lex->select_lex.ref_pointer_array, &tables,
fields, all_fields, (ORDER*) order->first) ||
!(sortorder=make_unireg_sortorder((ORDER*) order->first, &length)) ||
(table->sort.found_records = filesort(thd, table, sortorder, length,
select, HA_POS_ERROR,
&examined_rows))
== HA_POS_ERROR)
fields, all_fields, (ORDER*) order->first))
{
delete select;
free_underlaid_joins(thd, &thd->lex->select_lex);
DBUG_RETURN(-1); // This will force out message
}
/*
Filesort has already found and selected the rows we want to delete,
so we don't need the where clause
*/
delete select;
select= 0;
if (!select && limit != HA_POS_ERROR)
usable_index= get_index_for_order(table, (ORDER*)(order->first), limit);
if (usable_index == MAX_KEY)
{
table->sort.io_cache= (IO_CACHE *) my_malloc(sizeof(IO_CACHE),
MYF(MY_FAE | MY_ZEROFILL));
if ( !(sortorder=make_unireg_sortorder((ORDER*) order->first, &length)) ||
(table->sort.found_records = filesort(thd, table, sortorder, length,
select, HA_POS_ERROR,
&examined_rows))
== HA_POS_ERROR)
{
delete select;
free_underlaid_joins(thd, &thd->lex->select_lex);
DBUG_RETURN(-1); // This will force out message
}
/*
Filesort has already found and selected the rows we want to delete,
so we don't need the where clause
*/
delete select;
select= 0;
}
}
init_read_record(&info,thd,table,select,1,1);
if (usable_index==MAX_KEY)
init_read_record(&info,thd,table,select,1,1);
else
init_read_record_idx(&info, thd, table, 1, usable_index);
deleted=0L;
init_ftfuncs(thd, &thd->lex->select_lex, 1);
thd->proc_info="updating";