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Fixed bug mdev-7316.

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The function table_cond_selectivity() should take into account that condition selectivity
for some fields can be set to 0.
This commit is contained in:
Igor Babaev
2015-02-05 20:09:08 -08:00
parent 826d7c68d2
commit 587c72088c
4 changed files with 104 additions and 2 deletions
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36
mysql-test/r/selectivity.result
View File

@ -1409,4 +1409,40 @@ Note 1003 select `test`.`a`.`a` AS `a`,`test`.`a`.`b` AS `b`,`test`.`b`.`a` AS `
set histogram_size=@save_histogram_size;
set optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivity;
drop table t0,t1,t2;
#
# Bug mdev-7316: a conjunct in WHERE with selectivity == 0
#
CREATE TABLE t1 (a varchar(16), b int, PRIMARY KEY(a), KEY(b)) ENGINE=INNODB;
Warnings:
Warning 1286 Unknown storage engine 'INNODB'
Warning 1266 Using storage engine MyISAM for table 't1'
INSERT INTO t1 VALUES
('USAChinese',10), ('USAEnglish',20), ('USAFrench',30);
CREATE TABLE t2 (i int) ENGINE=INNODB;
Warnings:
Warning 1286 Unknown storage engine 'INNODB'
Warning 1266 Using storage engine MyISAM for table 't2'
INSERT INTO t2 VALUES
(1),(2),(3),(4),(5),(6),(7),(8),(9),(10),(1),(2),(3),(4);
ANALYZE TABLE t1, t2;
Table Op Msg_type Msg_text
test.t1 analyze status Engine-independent statistics collected
test.t1 analyze status OK
test.t2 analyze status Engine-independent statistics collected
test.t2 analyze status OK
set use_stat_tables='preferably';
set optimizer_use_condition_selectivity=3;
EXPLAIN EXTENDED
SELECT * FROM t1, t2
WHERE a <> 'USARussian' AND b IS NULL;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 ref PRIMARY,b b 5 const 1 100.00 Using index condition; Using where
1 SIMPLE t2 ALL NULL NULL NULL NULL 14 100.00 Using join buffer (flat, BNL join)
Warnings:
Note 1003 select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b`,`test`.`t2`.`i` AS `i` from `test`.`t1` join `test`.`t2` where ((`test`.`t1`.`a` <> 'USARussian') and isnull(`test`.`t1`.`b`))
SELECT * FROM t1, t2
WHERE a <> 'USARussian' AND b IS NULL;
a b i
set optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivity;
DROP TABLE t1,t2;
set use_stat_tables=@save_use_stat_tables;

30
mysql-test/r/selectivity_innodb.result
View File

@ -1419,6 +1419,36 @@ Note 1003 select `test`.`a`.`a` AS `a`,`test`.`a`.`b` AS `b`,`test`.`b`.`a` AS `
set histogram_size=@save_histogram_size;
set optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivity;
drop table t0,t1,t2;
#
# Bug mdev-7316: a conjunct in WHERE with selectivity == 0
#
CREATE TABLE t1 (a varchar(16), b int, PRIMARY KEY(a), KEY(b)) ENGINE=INNODB;
INSERT INTO t1 VALUES
('USAChinese',10), ('USAEnglish',20), ('USAFrench',30);
CREATE TABLE t2 (i int) ENGINE=INNODB;
INSERT INTO t2 VALUES
(1),(2),(3),(4),(5),(6),(7),(8),(9),(10),(1),(2),(3),(4);
ANALYZE TABLE t1, t2;
Table Op Msg_type Msg_text
test.t1 analyze status Engine-independent statistics collected
test.t1 analyze status OK
test.t2 analyze status Engine-independent statistics collected
test.t2 analyze status OK
set use_stat_tables='preferably';
set optimizer_use_condition_selectivity=3;
EXPLAIN EXTENDED
SELECT * FROM t1, t2
WHERE a <> 'USARussian' AND b IS NULL;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 ref PRIMARY,b b 5 const 2 66.67 Using where; Using index
1 SIMPLE t2 ALL NULL NULL NULL NULL 14 100.00 Using join buffer (flat, BNL join)
Warnings:
Note 1003 select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b`,`test`.`t2`.`i` AS `i` from `test`.`t1` join `test`.`t2` where ((`test`.`t1`.`a` <> 'USARussian') and isnull(`test`.`t1`.`b`))
SELECT * FROM t1, t2
WHERE a <> 'USARussian' AND b IS NULL;
a b i
set optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivity;
DROP TABLE t1,t2;
set use_stat_tables=@save_use_stat_tables;
set optimizer_switch=@save_optimizer_switch_for_selectivity_test;
set @tmp_ust= @@use_stat_tables;

29
mysql-test/t/selectivity.test
View File

@ -942,5 +942,34 @@ set optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivit
drop table t0,t1,t2;
--echo #
--echo # Bug mdev-7316: a conjunct in WHERE with selectivity == 0
--echo #
CREATE TABLE t1 (a varchar(16), b int, PRIMARY KEY(a), KEY(b)) ENGINE=INNODB;
INSERT INTO t1 VALUES
('USAChinese',10), ('USAEnglish',20), ('USAFrench',30);
CREATE TABLE t2 (i int) ENGINE=INNODB;
INSERT INTO t2 VALUES
(1),(2),(3),(4),(5),(6),(7),(8),(9),(10),(1),(2),(3),(4);
ANALYZE TABLE t1, t2;
set use_stat_tables='preferably';
set optimizer_use_condition_selectivity=3;
EXPLAIN EXTENDED
SELECT * FROM t1, t2
WHERE a <> 'USARussian' AND b IS NULL;
SELECT * FROM t1, t2
WHERE a <> 'USARussian' AND b IS NULL;
set optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivity;
DROP TABLE t1,t2;
set use_stat_tables=@save_use_stat_tables;

7
sql/sql_select.cc
View File

@ -7449,8 +7449,12 @@ double table_cond_selectivity(JOIN *join, uint idx, JOIN_TAB *s,
else
fldno= table->key_info[key].key_part[keyparts-1].fieldnr - 1;
if (keyuse->val->const_item())
{
if (table->field[fldno]->cond_selectivity > 0)
{
sel /= table->field[fldno]->cond_selectivity;
set_if_smaller(sel, 1.0);
}
/*
TODO: we could do better here:
1. cond_selectivity might be =1 (the default) because quick
@ -7504,7 +7508,10 @@ double table_cond_selectivity(JOIN *join, uint idx, JOIN_TAB *s,
if (!(next_field->table->map & rem_tables) && next_field->table != table)
{
if (field->cond_selectivity > 0)
{
sel/= field->cond_selectivity;
set_if_smaller(sel, 1.0);
}
break;
}
}