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Fixed bug mdev-5028.

Browse Source 
Apparently in a general case a short-cut for the distinct optimization
is invalid if join buffers are used to join tables after the tables whose
values are to selected.
This commit is contained in:
Igor Babaev
2013-10-02 17:59:56 -07:00
parent ec7da1561e
commit 00816a964f
5 changed files with 179 additions and 8 deletions
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110
mysql-test/r/distinct.result
View File

@@ -879,3 +879,113 @@ NULL
7 7
drop view v; drop view v;
drop table t1, t2; drop table t1, t2;
CREATE TABLE t1 (
id int, i1 int, i2 int DEFAULT 0,
d1 date DEFAULT '2000-01-01', d2 date DEFAULT '2000-01-01',
t1 time DEFAULT '00:00:00', t2 time DEFAULT '00:00:00',
dt1 datetime NOT NULL DEFAULT '2000-01-01 00:00:00',
dt2 datetime NOT NULL DEFAULT '2000-01-01 00:00:00',
c1 varchar(1) NOT NULL, c2 varchar(1) NOT NULL
) ENGINE=MyISAM;
CREATE ALGORITHM=TEMPTABLE VIEW v1 AS SELECT * FROM t1;
INSERT INTO t1 (id,i1,c1,c2) VALUES
(1,7,'t','t'),(2,4,'k','k'),(3,2,'e','e'),(4,0,'i','i'),(5,1,'t','t'),(6,91,'m','m'),
(7,6,'z','z'),(8,3,'c','c'),(9,6,'i','i'),(10,8,'v','v'), (11,1,'l','l'),(12,4,'j','j'),
(13,5,'w','w'),(14,0,'r','r'),(15,7,'o','o'),(16,9,'o','o'),(17,7,'u','u'),(18,6,'f','f'),
(19,0,'l','l'),(20,6,'g','g'),(21,1,'e','e'),(22,7,'y','y'),(23,0,'p','p'),(24,6,'v','v'),
(25,5,'d','d'),(26,9,'i','i'),(27,5,'z','z'),(28,2,'q','q'),(29,4,'j','j'),(30,9,'m','m'),
(31,8,'d','d'),(32,5,'r','r'),(33,1,'r','r'),(34,1,'k','k'),(35,4,'p','p'),(36,2,'x','x'),
(37,5,'w','w'),(38,0,'k','k'),(39,7,'y','y'),(40,4,'p','p'),(41,9,'l','l'),(42,2,'u','u'),
(43,3,'r','r'),(44,5,'y','y'),(45,3,'u','u'),(46,9,'t','t'),(47,8,'f','f'),(48,2,'f','f'),
(49,2,'q','q'),(50,6,'v','v'),(51,6,'u','u'),(52,0,'b','b'),(53,1,'n','n'),(54,2,'p','p'),
(55,0,'y','y'),(56,1,'l','l'),(57,1,'c','c'),(58,0,'d','d'),(59,2,'y','y'),(60,7,'l','l'),
(61,6,'m','m'),(62,9,'q','q'),(63,0,'j','j'),(64,3,'u','u'),(65,4,'w','w'),(66,5,'p','p'),
(67,8,'z','z'),(68,5,'u','u'),(69,7,'b','b'),(70,0,'f','f'),(71,6,'u','u'),(72,1,'i','i'),
(73,9,'s','s'),(74,3,'y','y'),(75,5,'s','s'),(76,8,'x','x'),(77,3,'s','s'),(78,3,'l','l'),
(79,8,'b','b'),(80,0,'p','p'),(81,9,'m','m'),(82,5,'k','k'),(83,7,'u','u'),(84,0,'y','y'),
(85,2,'x','x'),(86,5,'h','h'),(87,5,'j','j'),(88,5,'o','o'),(89,9,'o','o'),(90,1,'c','c'),
(91,7,'k','k'),(92,9,'t','t'),(93,3,'h','h'),(94,6,'g','g'),(95,9,'r','r'),(96,2,'i','i');
CREATE TABLE t2 (i INT) ENGINE=MyISAM;
INSERT INTO t2 VALUES (7),(8);
SELECT STRAIGHT_JOIN COUNT(DISTINCT t1.id) FROM
t1, v1, t2 WHERE v1.id = t2.i AND t1.i1 = v1.i1 AND t2.i != 3;
COUNT(DISTINCT t1.id)
18
EXPLAIN EXTENDED
SELECT STRAIGHT_JOIN DISTINCT t1.id FROM
t1, v1, t2 WHERE v1.id = t2.i AND t1.i1 = v1.i1 AND t2.i != 3;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 96 100.00 Using where; Using temporary
1 PRIMARY <derived2> ref key0 key0 5 test.t1.i1 9 100.00 Using where; Distinct
1 PRIMARY t2 ALL NULL NULL NULL NULL 2 100.00 Using where; Distinct; Using join buffer (flat, BNL join)
2 DERIVED t1 ALL NULL NULL NULL NULL 96 100.00
Warnings:
Note 1003 select straight_join distinct `test`.`t1`.`id` AS `id` from `test`.`t1` join `test`.`v1` join `test`.`t2` where ((`test`.`t2`.`i` = `v1`.`id`) and (`v1`.`i1` = `test`.`t1`.`i1`) and (`v1`.`id` <> 3))
set join_buffer_size=1024;
SELECT STRAIGHT_JOIN DISTINCT t1.id FROM
t1, v1, t2 WHERE v1.id = t2.i AND t1.i1 = v1.i1 AND t2.i != 3;
id
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set join_buffer_size=1024*16;
SELECT STRAIGHT_JOIN DISTINCT t1.id FROM
t1, v1, t2 WHERE v1.id = t2.i AND t1.i1 = v1.i1 AND t2.i != 3;
id
7
9
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24
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set join_buffer_size=default;
SELECT STRAIGHT_JOIN DISTINCT t1.id FROM
t1, v1, t2 WHERE v1.id = t2.i AND t1.i1 = v1.i1 AND t2.i != 3;
id
7
9
18
20
24
50
51
61
71
94
8
43
45
64
74
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78
93
DROP VIEW v1;
DROP TABLE t1,t2;

59
mysql-test/t/distinct.test
View File

@@ -682,3 +682,62 @@ select * from v;
select distinct (select max(a) from t1 where alias.b = a) as field1 from t2 as alias group by field1; select distinct (select max(a) from t1 where alias.b = a) as field1 from t2 as alias group by field1;
drop view v; drop view v;
drop table t1, t2; drop table t1, t2;
#
# Bug mdev-5028: invalid distinct optimization when join buffer is used
#
CREATE TABLE t1 (
id int, i1 int, i2 int DEFAULT 0,
d1 date DEFAULT '2000-01-01', d2 date DEFAULT '2000-01-01',
t1 time DEFAULT '00:00:00', t2 time DEFAULT '00:00:00',
dt1 datetime NOT NULL DEFAULT '2000-01-01 00:00:00',
dt2 datetime NOT NULL DEFAULT '2000-01-01 00:00:00',
c1 varchar(1) NOT NULL, c2 varchar(1) NOT NULL
) ENGINE=MyISAM;
CREATE ALGORITHM=TEMPTABLE VIEW v1 AS SELECT * FROM t1;
INSERT INTO t1 (id,i1,c1,c2) VALUES
(1,7,'t','t'),(2,4,'k','k'),(3,2,'e','e'),(4,0,'i','i'),(5,1,'t','t'),(6,91,'m','m'),
(7,6,'z','z'),(8,3,'c','c'),(9,6,'i','i'),(10,8,'v','v'), (11,1,'l','l'),(12,4,'j','j'),
(13,5,'w','w'),(14,0,'r','r'),(15,7,'o','o'),(16,9,'o','o'),(17,7,'u','u'),(18,6,'f','f'),
(19,0,'l','l'),(20,6,'g','g'),(21,1,'e','e'),(22,7,'y','y'),(23,0,'p','p'),(24,6,'v','v'),
(25,5,'d','d'),(26,9,'i','i'),(27,5,'z','z'),(28,2,'q','q'),(29,4,'j','j'),(30,9,'m','m'),
(31,8,'d','d'),(32,5,'r','r'),(33,1,'r','r'),(34,1,'k','k'),(35,4,'p','p'),(36,2,'x','x'),
(37,5,'w','w'),(38,0,'k','k'),(39,7,'y','y'),(40,4,'p','p'),(41,9,'l','l'),(42,2,'u','u'),
(43,3,'r','r'),(44,5,'y','y'),(45,3,'u','u'),(46,9,'t','t'),(47,8,'f','f'),(48,2,'f','f'),
(49,2,'q','q'),(50,6,'v','v'),(51,6,'u','u'),(52,0,'b','b'),(53,1,'n','n'),(54,2,'p','p'),
(55,0,'y','y'),(56,1,'l','l'),(57,1,'c','c'),(58,0,'d','d'),(59,2,'y','y'),(60,7,'l','l'),
(61,6,'m','m'),(62,9,'q','q'),(63,0,'j','j'),(64,3,'u','u'),(65,4,'w','w'),(66,5,'p','p'),
(67,8,'z','z'),(68,5,'u','u'),(69,7,'b','b'),(70,0,'f','f'),(71,6,'u','u'),(72,1,'i','i'),
(73,9,'s','s'),(74,3,'y','y'),(75,5,'s','s'),(76,8,'x','x'),(77,3,'s','s'),(78,3,'l','l'),
(79,8,'b','b'),(80,0,'p','p'),(81,9,'m','m'),(82,5,'k','k'),(83,7,'u','u'),(84,0,'y','y'),
(85,2,'x','x'),(86,5,'h','h'),(87,5,'j','j'),(88,5,'o','o'),(89,9,'o','o'),(90,1,'c','c'),
(91,7,'k','k'),(92,9,'t','t'),(93,3,'h','h'),(94,6,'g','g'),(95,9,'r','r'),(96,2,'i','i');
CREATE TABLE t2 (i INT) ENGINE=MyISAM;
INSERT INTO t2 VALUES (7),(8);
SELECT STRAIGHT_JOIN COUNT(DISTINCT t1.id) FROM
t1, v1, t2 WHERE v1.id = t2.i AND t1.i1 = v1.i1 AND t2.i != 3;
EXPLAIN EXTENDED
SELECT STRAIGHT_JOIN DISTINCT t1.id FROM
t1, v1, t2 WHERE v1.id = t2.i AND t1.i1 = v1.i1 AND t2.i != 3;
set join_buffer_size=1024;
SELECT STRAIGHT_JOIN DISTINCT t1.id FROM
t1, v1, t2 WHERE v1.id = t2.i AND t1.i1 = v1.i1 AND t2.i != 3;
set join_buffer_size=1024*16;
SELECT STRAIGHT_JOIN DISTINCT t1.id FROM
t1, v1, t2 WHERE v1.id = t2.i AND t1.i1 = v1.i1 AND t2.i != 3;
set join_buffer_size=default;
SELECT STRAIGHT_JOIN DISTINCT t1.id FROM
t1, v1, t2 WHERE v1.id = t2.i AND t1.i1 = v1.i1 AND t2.i != 3;
DROP VIEW v1;
DROP TABLE t1,t2;

2
sql/sql_cursor.cc
View File

@@ -398,7 +398,7 @@ Sensitive_cursor::open(JOIN *join_arg)
#ifndef DBUG_OFF #ifndef DBUG_OFF
JOIN_TAB *first_tab= first_linear_tab(join, WITHOUT_CONST_TABLES); JOIN_TAB *first_tab= first_linear_tab(join, WITHOUT_CONST_TABLES);
DBUG_ASSERT(first_tab->table->reginfo.not_exists_optimize == 0); DBUG_ASSERT(first_tab->table->reginfo.not_exists_optimize == 0);
DBUG_ASSERT(first_tab->not_used_in_distinct == 0); DBUG_ASSERT(first_tab->shortcut_for_distinct == 0);
/* /*
null_row is set only if row not found and it's outer join: should never null_row is set only if row not found and it's outer join: should never
happen for the first table in join_tab list happen for the first table in join_tab list

11
sql/sql_select.cc
View File

@@ -1811,9 +1811,10 @@ int JOIN::init_execution()
JOIN_TAB *last_join_tab= join_tab + top_join_tab_count - 1; JOIN_TAB *last_join_tab= join_tab + top_join_tab_count - 1;
do do
{ {
if (used_tables & last_join_tab->table->map) if (used_tables & last_join_tab->table->map ||
last_join_tab->use_join_cache)
break; break;
last_join_tab->not_used_in_distinct=1; last_join_tab->shortcut_for_distinct= true;
} while (last_join_tab-- != join_tab); } while (last_join_tab-- != join_tab);
/* Optimize "select distinct b from t1 order by key_part_1 limit #" */ /* Optimize "select distinct b from t1 order by key_part_1 limit #" */
if (order && skip_sort_order) if (order && skip_sort_order)
@@ -7983,7 +7984,7 @@ JOIN::make_simple_join(JOIN *parent, TABLE *temp_table)
join_tab->last_inner= 0; join_tab->last_inner= 0;
join_tab->first_unmatched= 0; join_tab->first_unmatched= 0;
join_tab->ref.key = -1; join_tab->ref.key = -1;
join_tab->not_used_in_distinct=0; join_tab->shortcut_for_distinct= false;
join_tab->read_first_record= join_init_read_record; join_tab->read_first_record= join_init_read_record;
join_tab->preread_init_done= FALSE; join_tab->preread_init_done= FALSE;
join_tab->join= this; join_tab->join= this;
@@ -16223,7 +16224,7 @@ static enum_nested_loop_state
evaluate_join_record(JOIN *join, JOIN_TAB *join_tab, evaluate_join_record(JOIN *join, JOIN_TAB *join_tab,
int error) int error)
{ {
bool not_used_in_distinct=join_tab->not_used_in_distinct; bool shortcut_for_distinct= join_tab->shortcut_for_distinct;
ha_rows found_records=join->found_records; ha_rows found_records=join->found_records;
COND *select_cond= join_tab->select_cond; COND *select_cond= join_tab->select_cond;
bool select_cond_result= TRUE; bool select_cond_result= TRUE;
@@ -16362,7 +16363,7 @@ evaluate_join_record(JOIN *join, JOIN_TAB *join_tab,
was not in the field list; In this case we can abort if was not in the field list; In this case we can abort if
we found a row, as no new rows can be added to the result. we found a row, as no new rows can be added to the result.
*/ */
if (not_used_in_distinct && found_records != join->found_records) if (shortcut_for_distinct && found_records != join->found_records)
DBUG_RETURN(NESTED_LOOP_NO_MORE_ROWS); DBUG_RETURN(NESTED_LOOP_NO_MORE_ROWS);
} }
else else

5
sql/sql_select.h
View File

@@ -314,8 +314,9 @@ typedef struct st_join_table {
uint used_null_fields; uint used_null_fields;
uint used_uneven_bit_fields; uint used_uneven_bit_fields;
enum join_type type; enum join_type type;
bool cached_eq_ref_table,eq_ref_table,not_used_in_distinct; bool cached_eq_ref_table,eq_ref_table;
bool sorted; bool shortcut_for_distinct;
bool sorted;
/* /*
If it's not 0 the number stored this field indicates that the index If it's not 0 the number stored this field indicates that the index
scan has been chosen to access the table data and we expect to scan scan has been chosen to access the table data and we expect to scan