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MWL#89: Cost-based choice between Materialization and IN->EXISTS transformation

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Fixes for multiple problems/bugs/test failures that resulted from moving
subquery optimization from the execution phase to the optimization phase.
This commit is contained in:
unknown
2010-09-05 18:43:47 +03:00
parent aa195b2570
commit 18ad3bdc2f
14 changed files with 528 additions and 269 deletions
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14
sql/sql_union.cc
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@ -186,6 +186,8 @@ st_select_lex_unit::init_prepare_fake_select_lex(THD *thd_arg)
{
(*order->item)->walk(&Item::change_context_processor, 0,
(uchar*) &fake_select_lex->context);
(*order->item)->walk(&Item::set_fake_select_as_master_processor, 0,
(uchar*) fake_select_lex);
}
}
@ -271,6 +273,18 @@ bool st_select_lex_unit::prepare(THD *thd_arg, select_result *sel_result,
can_skip_order_by= is_union_select && !(sl->braces && sl->explicit_limit);
/*
Remove all references from the select_lex_units to the subqueries that
are inside the ORDER BY clause.
*/
if (can_skip_order_by)
{
for (ORDER *ord= (ORDER *)sl->order_list.first; ord; ord= ord->next)
{
(*ord->item)->walk(&Item::eliminate_subselect_processor, FALSE, NULL);
}
}
saved_error= join->prepare(&sl->ref_pointer_array,
(TABLE_LIST*) sl->table_list.first,
sl->with_wild,