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MDEV-17518: Range optimization doesn't use ON expressions from nested outer joins

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Continuation of the fix: Make condition selectivity estimate use the
right estimate, too.
This commit is contained in:
Sergei Petrunia
2018-10-23 13:17:14 +02:00
parent 3b6d903852
commit 14b62b1578
3 changed files with 60 additions and 3 deletions
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32
mysql-test/main/join_outer.result
View File

@ -2531,5 +2531,37 @@ id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 10 1 SIMPLE t1 ALL NULL NULL NULL NULL 10
1 SIMPLE t2 ALL NULL NULL NULL NULL 2 1 SIMPLE t2 ALL NULL NULL NULL NULL 2
1 SIMPLE t3 range a a 5 NULL 5 Using where 1 SIMPLE t3 range a a 5 NULL 5 Using where
#
# .. part 2: make sure condition selectivity can use the condition too.
#
alter table t3 drop key a;
set @tmp1=@@optimizer_use_condition_selectivity;
set @tmp2=@@use_stat_tables;
set @tmp3=@@histogram_size;
set use_stat_tables=preferably;
set optimizer_use_condition_selectivity=4;
set histogram_size=100;
analyze table t3 persistent for all;
Table Op Msg_type Msg_text
test.t3 analyze status Engine-independent statistics collected
test.t3 analyze status OK
# t3.filtered is less than 100%:
explain extended select * from t1 left join t3 on t1.a=t3.b and t3.a<5;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 10 100.00
1 SIMPLE t3 ALL NULL NULL NULL NULL 1000 0.99 Using where
Warnings:
Note 1003 select `test`.`t1`.`a` AS `a`,`test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b` from `test`.`t1` left join `test`.`t3` on(`test`.`t3`.`b` = `test`.`t1`.`a` and `test`.`t3`.`a` < 5) where 1
# t3.filtered must less than 100%, too:
explain extended select * from t1 left join (t3 join t2) on t1.a=t3.b and t3.a<5;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 10 100.00
1 SIMPLE t2 ALL NULL NULL NULL NULL 2 100.00
1 SIMPLE t3 ALL NULL NULL NULL NULL 1000 0.99 Using where
Warnings:
Note 1003 select `test`.`t1`.`a` AS `a`,`test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b`,`test`.`t2`.`a` AS `a` from `test`.`t1` left join (`test`.`t3` join `test`.`t2`) on(`test`.`t3`.`b` = `test`.`t1`.`a` and `test`.`t3`.`a` < 5) where 1
drop table t1,t2,t3; drop table t1,t2,t3;
set optimizer_use_condition_selectivity= @tmp1;
set use_stat_tables= @tmp2;
set histogram_size= @tmp3;
SET optimizer_switch=@save_optimizer_switch; SET optimizer_switch=@save_optimizer_switch;

23
mysql-test/main/join_outer.test
View File

@ -2060,6 +2060,29 @@ explain select * from t1 left join t3 on t1.a=t3.b and t3.a<5;
--echo # This must use range for table t3, too: --echo # This must use range for table t3, too:
explain select * from t1 left join (t3 join t2) on t1.a=t3.b and t3.a<5; explain select * from t1 left join (t3 join t2) on t1.a=t3.b and t3.a<5;
--echo #
--echo # .. part 2: make sure condition selectivity can use the condition too.
--echo #
alter table t3 drop key a;
set @tmp1=@@optimizer_use_condition_selectivity;
set @tmp2=@@use_stat_tables;
set @tmp3=@@histogram_size;
set use_stat_tables=preferably;
set optimizer_use_condition_selectivity=4;
set histogram_size=100;
analyze table t3 persistent for all;
--echo # t3.filtered is less than 100%:
explain extended select * from t1 left join t3 on t1.a=t3.b and t3.a<5;
--echo # t3.filtered must less than 100%, too:
explain extended select * from t1 left join (t3 join t2) on t1.a=t3.b and t3.a<5;
drop table t1,t2,t3; drop table t1,t2,t3;
set optimizer_use_condition_selectivity= @tmp1;
set use_stat_tables= @tmp2;
set histogram_size= @tmp3;
SET optimizer_switch=@save_optimizer_switch; SET optimizer_switch=@save_optimizer_switch;

8
sql/sql_select.cc
View File

@ -4951,9 +4951,10 @@ make_join_statistics(JOIN *join, List<TABLE_LIST> &tables_list,
bool impossible_range= FALSE; bool impossible_range= FALSE;
ha_rows records= HA_POS_ERROR; ha_rows records= HA_POS_ERROR;
SQL_SELECT *select= 0; SQL_SELECT *select= 0;
Item **sargable_cond= NULL;
if (!s->const_keys.is_clear_all()) if (!s->const_keys.is_clear_all())
{ {
Item **sargable_cond= get_sargable_cond(join, s->table); sargable_cond= get_sargable_cond(join, s->table);
select= make_select(s->table, found_const_table_map, select= make_select(s->table, found_const_table_map,
found_const_table_map, found_const_table_map,
@ -4978,10 +4979,11 @@ make_join_statistics(JOIN *join, List<TABLE_LIST> &tables_list,
} }
if (!impossible_range) if (!impossible_range)
{ {
if (!sargable_cond)
sargable_cond= get_sargable_cond(join, s->table);
if (join->thd->variables.optimizer_use_condition_selectivity > 1) if (join->thd->variables.optimizer_use_condition_selectivity > 1)
calculate_cond_selectivity_for_table(join->thd, s->table, calculate_cond_selectivity_for_table(join->thd, s->table,
*s->on_expr_ref ? sargable_cond);
s->on_expr_ref : &join->conds);
if (s->table->reginfo.impossible_range) if (s->table->reginfo.impossible_range)
{ {
impossible_range= TRUE; impossible_range= TRUE;