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Fixed bug mdev-4367.

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When calculating selectivity of conditions one should take into account
the cases when some tables to be joined are empty.
This commit is contained in:
Igor Babaev 2013-04-03 23:50:14 -07:00
parent d62ee4e970
commit 50d4d1ca18
5 changed files with 57 additions and 7 deletions
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14
mysql-test/r/selectivity.result
View file

@ -750,4 +750,18 @@ drop table t1;
set histogram_size=@save_histogram_size;
set histogram_type=@save_histogram_type;
set optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivity;
#
# Bug mdev-4367: join of a merged empty derived table
# when optimizer_use_condition_selectivity=3
#
SET optimizer_use_condition_selectivity=3;
CREATE TABLE t1 (a varchar(1)) ENGINE=MyISAM;
INSERT INTO t1 VALUES ('j'),('k');
CREATE TABLE t2 (b varchar(1)) ENGINE=MyISAM;
INSERT INTO t2 VALUES ('x'),('y');
CREATE TABLE t3 (c varchar(1), KEY(c)) ENGINE=MyISAM;
SELECT * FROM t1 STRAIGHT_JOIN (t2 JOIN t3 ON c = b AND b > 'z');
a b c
DROP TABLE t1,t2,t3;
set optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivity;
set use_stat_tables=@save_use_stat_tables;

14
mysql-test/r/selectivity_innodb.result
View file

@ -757,6 +757,20 @@ drop table t1;
set histogram_size=@save_histogram_size;
set histogram_type=@save_histogram_type;
set optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivity;
#
# Bug mdev-4367: join of a merged empty derived table
# when optimizer_use_condition_selectivity=3
#
SET optimizer_use_condition_selectivity=3;
CREATE TABLE t1 (a varchar(1)) ENGINE=MyISAM;
INSERT INTO t1 VALUES ('j'),('k');
CREATE TABLE t2 (b varchar(1)) ENGINE=MyISAM;
INSERT INTO t2 VALUES ('x'),('y');
CREATE TABLE t3 (c varchar(1), KEY(c)) ENGINE=MyISAM;
SELECT * FROM t1 STRAIGHT_JOIN (t2 JOIN t3 ON c = b AND b > 'z');
a b c
DROP TABLE t1,t2,t3;
set optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivity;
set use_stat_tables=@save_use_stat_tables;
set optimizer_switch=@save_optimizer_switch_for_selectivity_test;
SET SESSION STORAGE_ENGINE=DEFAULT;

22
mysql-test/t/selectivity.test
View file

@ -336,4 +336,26 @@ set histogram_size=@save_histogram_size;
set histogram_type=@save_histogram_type;
set optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivity;
--echo #
--echo # Bug mdev-4367: join of a merged empty derived table
--echo # when optimizer_use_condition_selectivity=3
--echo #
SET optimizer_use_condition_selectivity=3;
CREATE TABLE t1 (a varchar(1)) ENGINE=MyISAM;
INSERT INTO t1 VALUES ('j'),('k');
CREATE TABLE t2 (b varchar(1)) ENGINE=MyISAM;
INSERT INTO t2 VALUES ('x'),('y');
CREATE TABLE t3 (c varchar(1), KEY(c)) ENGINE=MyISAM;
SELECT * FROM t1 STRAIGHT_JOIN (t2 JOIN t3 ON c = b AND b > 'z');
DROP TABLE t1,t2,t3;
set optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivity;
set use_stat_tables=@save_use_stat_tables;

12
sql/opt_range.cc
View file

@ -3324,6 +3324,12 @@ bool calculate_cond_selectivity_for_table(THD *thd, TABLE *table, Item *cond)
DBUG_ENTER("calculate_cond_selectivity_for_table");
table->cond_selectivity= 1.0;
#if 0
#else
if (table_records == 0)
DBUG_RETURN(FALSE);
#endif
if (thd->variables.optimizer_use_condition_selectivity > 2 &&
!bitmap_is_clear_all(used_fields))
@ -3363,11 +3369,6 @@ bool calculate_cond_selectivity_for_table(THD *thd, TABLE *table, Item *cond)
double rows;
if (*key)
{
#if 0
rows= records_in_column_ranges(&param, idx, *key);
if (rows != HA_POS_ERROR)
(*key)->field->cond_selectivity= rows/table_records;
#else
table->reginfo.impossible_range= 0;
if ((*key)->type == SEL_ARG::IMPOSSIBLE)
{
@ -3381,7 +3382,6 @@ bool calculate_cond_selectivity_for_table(THD *thd, TABLE *table, Item *cond)
if (rows != HA_POS_ERROR)
(*key)->field->cond_selectivity= rows/table_records;
}
#endif
}
}

2
sql/sql_select.cc
View file

@ -3795,7 +3795,7 @@ make_join_statistics(JOIN *join, List<TABLE_LIST> &tables_list,
*/
add_group_and_distinct_keys(join, s);
table->cond_selectivity= 1.0;
s->table->cond_selectivity= 1.0;
/*
Perform range analysis if there are keys it could use (1).