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MWL#89: Address review feedback (by Sergey Petrunia)

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mysql-test/r/subselect4.result:
  Moved test case for LP BUG#718593 into the correct test file subselect_mat_cost_bugs.test.
mysql-test/t/subselect4.test:
  Moved test case for LP BUG#718593 into the correct test file subselect_mat_cost_bugs.test.
This commit is contained in:
unknown
2011-05-23 10:56:05 +03:00
parent 56c0e19ed0
commit 742dfc92a2
11 changed files with 187 additions and 178 deletions
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70
sql/opt_subselect.cc
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@@ -205,18 +205,19 @@ int check_and_do_in_subquery_rewrites(JOIN *join)
!optimizer_flag(thd, OPTIMIZER_SWITCH_MATERIALIZATION))
my_error(ER_ILLEGAL_SUBQUERY_OPTIMIZER_SWITCHES, MYF(0));
/*
If the subquery predicate is IN/=ANY, analyse and set all possible
subquery execution strategies based on optimizer switches and syntactic
properties.
*/
if (in_subs)
{
/* Subquery predicate is an IN/=ANY predicate. */
if (optimizer_flag(thd, OPTIMIZER_SWITCH_IN_TO_EXISTS))
in_subs->in_strategy|= SUBS_IN_TO_EXISTS;
if (optimizer_flag(thd, OPTIMIZER_SWITCH_MATERIALIZATION))
in_subs->in_strategy|= SUBS_MATERIALIZATION;
/*
Check if the subquery predicate can be executed via materialization.
The required conditions are:
1. Subquery is a single SELECT (not a UNION)
0. The materialization optimizer switch was set.
1. Subquery is a single SELECT (not a UNION).
TODO: this is a limitation that can be fixed
2. Subquery is not a table-less query. In this case there is no
point in materializing.
2A The upper query is not a table-less SELECT ... FROM DUAL. We
@@ -230,7 +231,7 @@ int check_and_do_in_subquery_rewrites(JOIN *join)
non-top-level queries because it cannot handle NULLs correctly.
4. Subquery is non-correlated
TODO:
This is an overly restrictive condition. It can be extended to:
This condition is too restrictive (limitation). It can be extended to:
(Subquery is non-correlated ||
Subquery is correlated to any query outer to IN predicate ||
(Subquery is correlated to the immediate outer query &&
@@ -240,30 +241,30 @@ int check_and_do_in_subquery_rewrites(JOIN *join)
(*) The subquery must be part of a SELECT statement. The current
condition also excludes multi-table update statements.
*/
if (!(in_subs->in_strategy & SUBS_MATERIALIZATION &&
!select_lex->is_part_of_union() && // 1
parent_unit->first_select()->leaf_tables && // 2
thd->lex->sql_command == SQLCOM_SELECT && // *
select_lex->outer_select()->leaf_tables && // 2A
subquery_types_allow_materialization(in_subs) &&
// psergey-todo: duplicated_subselect_card_check: where it's done?
(in_subs->is_top_level_item() || //3
optimizer_flag(thd,
OPTIMIZER_SWITCH_PARTIAL_MATCH_ROWID_MERGE) || //3
optimizer_flag(thd,
OPTIMIZER_SWITCH_PARTIAL_MATCH_TABLE_SCAN)) && //3
!in_subs->is_correlated)) //4
if (optimizer_flag(thd, OPTIMIZER_SWITCH_MATERIALIZATION) && // 0
!select_lex->is_part_of_union() && // 1
parent_unit->first_select()->leaf_tables && // 2
thd->lex->sql_command == SQLCOM_SELECT && // *
select_lex->outer_select()->leaf_tables && // 2A
subquery_types_allow_materialization(in_subs) &&
(in_subs->is_top_level_item() || //3
optimizer_flag(thd,
OPTIMIZER_SWITCH_PARTIAL_MATCH_ROWID_MERGE) || //3
optimizer_flag(thd,
OPTIMIZER_SWITCH_PARTIAL_MATCH_TABLE_SCAN)) && //3
!in_subs->is_correlated) //4
{
/* Materialization is not possible based on syntactic properties. */
in_subs->in_strategy&= ~SUBS_MATERIALIZATION;
in_subs->in_strategy|= SUBS_MATERIALIZATION;
}
if (!in_subs->in_strategy)
/*
IN-TO-EXISTS is the only universal strategy. Choose it if the user
allowed it via an optimizer switch, or if materialization is not
possible.
*/
if (optimizer_flag(thd, OPTIMIZER_SWITCH_IN_TO_EXISTS) ||
!in_subs->in_strategy)
{
/*
If neither materialization is possible, nor the user chose
IN-TO-EXISTS, choose IN-TO-EXISTS as the only universal strategy.
*/
in_subs->in_strategy|= SUBS_IN_TO_EXISTS;
}
}
@@ -3703,10 +3704,9 @@ bool JOIN::choose_subquery_plan(table_map join_tables)
enum_reopt_result reopt_result= REOPT_NONE;
Item_in_subselect *in_subs;
if (select_lex->master_unit()->item &&
select_lex->master_unit()->item->is_in_predicate())
if (is_in_subquery())
{
in_subs= (Item_in_subselect*) select_lex->master_unit()->item;
in_subs= (Item_in_subselect*) unit->item;
if (in_subs->create_in_to_exists_cond(this))
return true;
}
@@ -3943,11 +3943,10 @@ bool JOIN::choose_subquery_plan(table_map join_tables)
bool JOIN::choose_tableless_subquery_plan()
{
DBUG_ASSERT(!tables_list || !tables);
if (select_lex->master_unit()->item)
if (unit->item)
{
DBUG_ASSERT(select_lex->master_unit()->item->type() ==
Item::SUBSELECT_ITEM);
Item_subselect *subs_predicate= select_lex->master_unit()->item;
DBUG_ASSERT(unit->item->type() == Item::SUBSELECT_ITEM);
Item_subselect *subs_predicate= unit->item;
/*
If the optimizer determined that his query has an empty result,
@@ -3990,4 +3989,3 @@ bool JOIN::choose_tableless_subquery_plan()
}
return FALSE;
}