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Fixed bug mdev-6292.

Browse Source 
Avoided exponential recursive calls of JOIN_CACHE::join_records() in the case
of non-nested outer joins.
A different solution is required to resolve this performance problem for
nested outer joins.
This commit is contained in:
Igor Babaev
2014-09-09 16:44:54 -07:00
parent 20fff8e5bd
commit 5023bb899d
5 changed files with 283 additions and 5 deletions
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149
mysql-test/r/join_cache.result
View File

@ -5636,4 +5636,153 @@ c
set join_buffer_size=default; set join_buffer_size=default;
set optimizer_switch=@tmp_optimizer_switch; set optimizer_switch=@tmp_optimizer_switch;
DROP table t1,t2,t3; DROP table t1,t2,t3;
#
# mdev-6292: huge performance degradation for a sequence
# of LEFT JOIN operations when using join buffer
#
CREATE TABLE t1 (
id int(11) NOT NULL AUTO_INCREMENT,
col1 varchar(255) NOT NULL DEFAULT '',
PRIMARY KEY (id)
) ENGINE=INNODB;
CREATE TABLE t2 (
id int(11) NOT NULL AUTO_INCREMENT,
parent_id smallint(3) NOT NULL DEFAULT '0',
col2 varchar(25) NOT NULL DEFAULT '',
PRIMARY KEY (id)
) ENGINE=INNODB;
set join_buffer_size=8192;
set join_cache_level=0;
set @init_time:=now();
SELECT t.*
FROM
t1 t
LEFT JOIN t2 c1 ON c1.parent_id = t.id AND c1.col2 = "val"
LEFT JOIN t2 c2 ON c2.parent_id = t.id AND c2.col2 = "val"
LEFT JOIN t2 c3 ON c3.parent_id = t.id AND c3.col2 = "val"
LEFT JOIN t2 c4 ON c4.parent_id = t.id AND c4.col2 = "val"
LEFT JOIN t2 c5 ON c5.parent_id = t.id AND c5.col2 = "val"
LEFT JOIN t2 c6 ON c6.parent_id = t.id AND c6.col2 = "val"
LEFT JOIN t2 c7 ON c7.parent_id = t.id AND c7.col2 = "val"
LEFT JOIN t2 c8 ON c8.parent_id = t.id AND c8.col2 = "val"
LEFT JOIN t2 c9 ON c9.parent_id = t.id AND c9.col2 = "val"
LEFT JOIN t2 c10 ON c10.parent_id = t.id AND c10.col2 = "val"
LEFT JOIN t2 c11 ON c11.parent_id = t.id AND c11.col2 = "val"
LEFT JOIN t2 c12 ON c12.parent_id = t.id AND c12.col2 = "val"
LEFT JOIN t2 c13 ON c13.parent_id = t.id AND c13.col2 = "val"
LEFT JOIN t2 c14 ON c14.parent_id = t.id AND c14.col2 = "val"
LEFT JOIN t2 c15 ON c15.parent_id = t.id AND c15.col2 = "val"
LEFT JOIN t2 c16 ON c16.parent_id = t.id AND c16.col2 = "val"
LEFT JOIN t2 c17 ON c17.parent_id = t.id AND c17.col2 = "val"
LEFT JOIN t2 c18 ON c18.parent_id = t.id AND c18.col2 = "val"
LEFT JOIN t2 c19 ON c19.parent_id = t.id AND c19.col2 = "val"
LEFT JOIN t2 c20 ON c20.parent_id = t.id AND c20.col2 = "val"
LEFT JOIN t2 c21 ON c21.parent_id = t.id AND c21.col2 = "val"
LEFT JOIN t2 c22 ON c22.parent_id = t.id AND c22.col2 = "val"
LEFT JOIN t2 c23 ON c23.parent_id = t.id AND c23.col2 = "val"
LEFT JOIN t2 c24 ON c24.parent_id = t.id AND c24.col2 = "val"
LEFT JOIN t2 c25 ON c25.parent_id = t.id AND c25.col2 = "val"
ORDER BY
col1;
id col1
select timestampdiff(second, @init_time, now()) <= 1;
timestampdiff(second, @init_time, now()) <= 1
1
set join_cache_level=2;
set @init_time:=now();
SELECT t.*
FROM
t1 t
LEFT JOIN t2 c1 ON c1.parent_id = t.id AND c1.col2 = "val"
LEFT JOIN t2 c2 ON c2.parent_id = t.id AND c2.col2 = "val"
LEFT JOIN t2 c3 ON c3.parent_id = t.id AND c3.col2 = "val"
LEFT JOIN t2 c4 ON c4.parent_id = t.id AND c4.col2 = "val"
LEFT JOIN t2 c5 ON c5.parent_id = t.id AND c5.col2 = "val"
LEFT JOIN t2 c6 ON c6.parent_id = t.id AND c6.col2 = "val"
LEFT JOIN t2 c7 ON c7.parent_id = t.id AND c7.col2 = "val"
LEFT JOIN t2 c8 ON c8.parent_id = t.id AND c8.col2 = "val"
LEFT JOIN t2 c9 ON c9.parent_id = t.id AND c9.col2 = "val"
LEFT JOIN t2 c10 ON c10.parent_id = t.id AND c10.col2 = "val"
LEFT JOIN t2 c11 ON c11.parent_id = t.id AND c11.col2 = "val"
LEFT JOIN t2 c12 ON c12.parent_id = t.id AND c12.col2 = "val"
LEFT JOIN t2 c13 ON c13.parent_id = t.id AND c13.col2 = "val"
LEFT JOIN t2 c14 ON c14.parent_id = t.id AND c14.col2 = "val"
LEFT JOIN t2 c15 ON c15.parent_id = t.id AND c15.col2 = "val"
LEFT JOIN t2 c16 ON c16.parent_id = t.id AND c16.col2 = "val"
LEFT JOIN t2 c17 ON c17.parent_id = t.id AND c17.col2 = "val"
LEFT JOIN t2 c18 ON c18.parent_id = t.id AND c18.col2 = "val"
LEFT JOIN t2 c19 ON c19.parent_id = t.id AND c19.col2 = "val"
LEFT JOIN t2 c20 ON c20.parent_id = t.id AND c20.col2 = "val"
LEFT JOIN t2 c21 ON c21.parent_id = t.id AND c21.col2 = "val"
LEFT JOIN t2 c22 ON c22.parent_id = t.id AND c22.col2 = "val"
LEFT JOIN t2 c23 ON c23.parent_id = t.id AND c23.col2 = "val"
LEFT JOIN t2 c24 ON c24.parent_id = t.id AND c24.col2 = "val"
LEFT JOIN t2 c25 ON c25.parent_id = t.id AND c25.col2 = "val"
ORDER BY
col1;
id col1
select timestampdiff(second, @init_time, now()) <= 1;
timestampdiff(second, @init_time, now()) <= 1
1
EXPLAIN
SELECT t.*
FROM
t1 t
LEFT JOIN t2 c1 ON c1.parent_id = t.id AND c1.col2 = "val"
LEFT JOIN t2 c2 ON c2.parent_id = t.id AND c2.col2 = "val"
LEFT JOIN t2 c3 ON c3.parent_id = t.id AND c3.col2 = "val"
LEFT JOIN t2 c4 ON c4.parent_id = t.id AND c4.col2 = "val"
LEFT JOIN t2 c5 ON c5.parent_id = t.id AND c5.col2 = "val"
LEFT JOIN t2 c6 ON c6.parent_id = t.id AND c6.col2 = "val"
LEFT JOIN t2 c7 ON c7.parent_id = t.id AND c7.col2 = "val"
LEFT JOIN t2 c8 ON c8.parent_id = t.id AND c8.col2 = "val"
LEFT JOIN t2 c9 ON c9.parent_id = t.id AND c9.col2 = "val"
LEFT JOIN t2 c10 ON c10.parent_id = t.id AND c10.col2 = "val"
LEFT JOIN t2 c11 ON c11.parent_id = t.id AND c11.col2 = "val"
LEFT JOIN t2 c12 ON c12.parent_id = t.id AND c12.col2 = "val"
LEFT JOIN t2 c13 ON c13.parent_id = t.id AND c13.col2 = "val"
LEFT JOIN t2 c14 ON c14.parent_id = t.id AND c14.col2 = "val"
LEFT JOIN t2 c15 ON c15.parent_id = t.id AND c15.col2 = "val"
LEFT JOIN t2 c16 ON c16.parent_id = t.id AND c16.col2 = "val"
LEFT JOIN t2 c17 ON c17.parent_id = t.id AND c17.col2 = "val"
LEFT JOIN t2 c18 ON c18.parent_id = t.id AND c18.col2 = "val"
LEFT JOIN t2 c19 ON c19.parent_id = t.id AND c19.col2 = "val"
LEFT JOIN t2 c20 ON c20.parent_id = t.id AND c20.col2 = "val"
LEFT JOIN t2 c21 ON c21.parent_id = t.id AND c21.col2 = "val"
LEFT JOIN t2 c22 ON c22.parent_id = t.id AND c22.col2 = "val"
LEFT JOIN t2 c23 ON c23.parent_id = t.id AND c23.col2 = "val"
LEFT JOIN t2 c24 ON c24.parent_id = t.id AND c24.col2 = "val"
LEFT JOIN t2 c25 ON c25.parent_id = t.id AND c25.col2 = "val"
ORDER BY
col1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t ALL NULL NULL NULL NULL 1 Using temporary; Using filesort
1 SIMPLE c1 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (flat, BNL join)
1 SIMPLE c2 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join)
1 SIMPLE c3 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join)
1 SIMPLE c4 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join)
1 SIMPLE c5 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join)
1 SIMPLE c6 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join)
1 SIMPLE c7 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join)
1 SIMPLE c8 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join)
1 SIMPLE c9 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join)
1 SIMPLE c10 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join)
1 SIMPLE c11 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join)
1 SIMPLE c12 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join)
1 SIMPLE c13 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join)
1 SIMPLE c14 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join)
1 SIMPLE c15 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join)
1 SIMPLE c16 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join)
1 SIMPLE c17 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join)
1 SIMPLE c18 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join)
1 SIMPLE c19 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join)
1 SIMPLE c20 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join)
1 SIMPLE c21 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join)
1 SIMPLE c22 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join)
1 SIMPLE c23 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join)
1 SIMPLE c24 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join)
1 SIMPLE c25 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join)
set join_buffer_size=default;
set join_cache_level = default;
DROP TABLE t1,t2;
set @@optimizer_switch=@save_optimizer_switch; set @@optimizer_switch=@save_optimizer_switch;

6
mysql-test/r/join_nested_jcl6.result
View File

@ -705,18 +705,18 @@ t0.b=t1.b AND
(t8.b=t9.b OR t8.c IS NULL) AND (t8.b=t9.b OR t8.c IS NULL) AND
(t9.a=1); (t9.a=1);
a b a b a b a b a b a b a b a b a b a b a b a b a b a b a b a b a b a b a b a b
1 2 3 2 4 2 1 2 3 2 2 2 6 2 2 2 0 2 1 2
1 2 3 2 4 2 1 2 4 2 2 2 6 2 2 2 0 2 1 2
1 2 3 2 4 2 1 2 3 2 3 1 6 2 1 1 NULL NULL 1 1 1 2 3 2 4 2 1 2 3 2 3 1 6 2 1 1 NULL NULL 1 1
1 2 3 2 4 2 1 2 4 2 3 1 6 2 1 1 NULL NULL 1 1 1 2 3 2 4 2 1 2 4 2 3 1 6 2 1 1 NULL NULL 1 1
1 2 3 2 4 2 1 2 3 2 2 2 6 2 2 2 0 2 1 2
1 2 3 2 4 2 1 2 4 2 2 2 6 2 2 2 0 2 1 2
1 2 3 2 4 2 1 2 3 2 3 1 6 2 1 1 NULL NULL 1 2 1 2 3 2 4 2 1 2 3 2 3 1 6 2 1 1 NULL NULL 1 2
1 2 3 2 4 2 1 2 4 2 3 1 6 2 1 1 NULL NULL 1 2 1 2 3 2 4 2 1 2 4 2 3 1 6 2 1 1 NULL NULL 1 2
1 2 3 2 4 2 1 2 3 2 3 3 NULL NULL NULL NULL NULL NULL 1 1 1 2 3 2 4 2 1 2 3 2 3 3 NULL NULL NULL NULL NULL NULL 1 1
1 2 3 2 4 2 1 2 4 2 3 3 NULL NULL NULL NULL NULL NULL 1 1 1 2 3 2 4 2 1 2 4 2 3 3 NULL NULL NULL NULL NULL NULL 1 1
1 2 3 2 4 2 1 2 3 2 3 3 NULL NULL NULL NULL NULL NULL 1 2 1 2 3 2 4 2 1 2 3 2 3 3 NULL NULL NULL NULL NULL NULL 1 2
1 2 3 2 4 2 1 2 4 2 3 3 NULL NULL NULL NULL NULL NULL 1 2 1 2 3 2 4 2 1 2 4 2 3 3 NULL NULL NULL NULL NULL NULL 1 2
1 2 3 2 5 3 NULL NULL NULL NULL 2 2 6 2 2 2 0 2 1 2
1 2 3 2 5 3 NULL NULL NULL NULL 3 1 6 2 1 1 NULL NULL 1 1 1 2 3 2 5 3 NULL NULL NULL NULL 3 1 6 2 1 1 NULL NULL 1 1
1 2 3 2 5 3 NULL NULL NULL NULL 2 2 6 2 2 2 0 2 1 2
1 2 3 2 5 3 NULL NULL NULL NULL 3 1 6 2 1 1 NULL NULL 1 2 1 2 3 2 5 3 NULL NULL NULL NULL 3 1 6 2 1 1 NULL NULL 1 2
1 2 3 2 5 3 NULL NULL NULL NULL 3 3 NULL NULL NULL NULL NULL NULL 1 1 1 2 3 2 5 3 NULL NULL NULL NULL 3 3 NULL NULL NULL NULL NULL NULL 1 1
1 2 3 2 5 3 NULL NULL NULL NULL 3 3 NULL NULL NULL NULL NULL NULL 1 2 1 2 3 2 5 3 NULL NULL NULL NULL 3 3 NULL NULL NULL NULL NULL NULL 1 2

2
mysql-test/r/join_outer_jcl6.result
View File

@ -696,9 +696,9 @@ insert into t2 values (1,3), (2,3);
insert into t3 values (2,4), (3,4); insert into t3 values (2,4), (3,4);
select * from t1 left join t2 on b1 = a1 left join t3 on c1 = a1 and b1 is null; select * from t1 left join t2 on b1 = a1 left join t3 on c1 = a1 and b1 is null;
a1 a2 b1 b2 c1 c2 a1 a2 b1 b2 c1 c2
3 2 NULL NULL 3 4
1 2 1 3 NULL NULL 1 2 1 3 NULL NULL
2 2 2 3 NULL NULL 2 2 2 3 NULL NULL
3 2 NULL NULL 3 4
explain select * from t1 left join t2 on b1 = a1 left join t3 on c1 = a1 and b1 is null; explain select * from t1 left join t2 on b1 = a1 left join t3 on c1 = a1 and b1 is null;
id select_type table type possible_keys key key_len ref rows Extra id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 3 1 SIMPLE t1 ALL NULL NULL NULL NULL 3

129
mysql-test/t/join_cache.test
View File

@ -3636,5 +3636,134 @@ set optimizer_switch=@tmp_optimizer_switch;
DROP table t1,t2,t3; DROP table t1,t2,t3;
--echo #
--echo # mdev-6292: huge performance degradation for a sequence
--echo # of LEFT JOIN operations when using join buffer
--echo #
--source include/have_innodb.inc
CREATE TABLE t1 (
id int(11) NOT NULL AUTO_INCREMENT,
col1 varchar(255) NOT NULL DEFAULT '',
PRIMARY KEY (id)
) ENGINE=INNODB;
CREATE TABLE t2 (
id int(11) NOT NULL AUTO_INCREMENT,
parent_id smallint(3) NOT NULL DEFAULT '0',
col2 varchar(25) NOT NULL DEFAULT '',
PRIMARY KEY (id)
) ENGINE=INNODB;
set join_buffer_size=8192;
set join_cache_level=0;
set @init_time:=now();
SELECT t.*
FROM
t1 t
LEFT JOIN t2 c1 ON c1.parent_id = t.id AND c1.col2 = "val"
LEFT JOIN t2 c2 ON c2.parent_id = t.id AND c2.col2 = "val"
LEFT JOIN t2 c3 ON c3.parent_id = t.id AND c3.col2 = "val"
LEFT JOIN t2 c4 ON c4.parent_id = t.id AND c4.col2 = "val"
LEFT JOIN t2 c5 ON c5.parent_id = t.id AND c5.col2 = "val"
LEFT JOIN t2 c6 ON c6.parent_id = t.id AND c6.col2 = "val"
LEFT JOIN t2 c7 ON c7.parent_id = t.id AND c7.col2 = "val"
LEFT JOIN t2 c8 ON c8.parent_id = t.id AND c8.col2 = "val"
LEFT JOIN t2 c9 ON c9.parent_id = t.id AND c9.col2 = "val"
LEFT JOIN t2 c10 ON c10.parent_id = t.id AND c10.col2 = "val"
LEFT JOIN t2 c11 ON c11.parent_id = t.id AND c11.col2 = "val"
LEFT JOIN t2 c12 ON c12.parent_id = t.id AND c12.col2 = "val"
LEFT JOIN t2 c13 ON c13.parent_id = t.id AND c13.col2 = "val"
LEFT JOIN t2 c14 ON c14.parent_id = t.id AND c14.col2 = "val"
LEFT JOIN t2 c15 ON c15.parent_id = t.id AND c15.col2 = "val"
LEFT JOIN t2 c16 ON c16.parent_id = t.id AND c16.col2 = "val"
LEFT JOIN t2 c17 ON c17.parent_id = t.id AND c17.col2 = "val"
LEFT JOIN t2 c18 ON c18.parent_id = t.id AND c18.col2 = "val"
LEFT JOIN t2 c19 ON c19.parent_id = t.id AND c19.col2 = "val"
LEFT JOIN t2 c20 ON c20.parent_id = t.id AND c20.col2 = "val"
LEFT JOIN t2 c21 ON c21.parent_id = t.id AND c21.col2 = "val"
LEFT JOIN t2 c22 ON c22.parent_id = t.id AND c22.col2 = "val"
LEFT JOIN t2 c23 ON c23.parent_id = t.id AND c23.col2 = "val"
LEFT JOIN t2 c24 ON c24.parent_id = t.id AND c24.col2 = "val"
LEFT JOIN t2 c25 ON c25.parent_id = t.id AND c25.col2 = "val"
ORDER BY
col1;
select timestampdiff(second, @init_time, now()) <= 1;
set join_cache_level=2;
set @init_time:=now();
SELECT t.*
FROM
t1 t
LEFT JOIN t2 c1 ON c1.parent_id = t.id AND c1.col2 = "val"
LEFT JOIN t2 c2 ON c2.parent_id = t.id AND c2.col2 = "val"
LEFT JOIN t2 c3 ON c3.parent_id = t.id AND c3.col2 = "val"
LEFT JOIN t2 c4 ON c4.parent_id = t.id AND c4.col2 = "val"
LEFT JOIN t2 c5 ON c5.parent_id = t.id AND c5.col2 = "val"
LEFT JOIN t2 c6 ON c6.parent_id = t.id AND c6.col2 = "val"
LEFT JOIN t2 c7 ON c7.parent_id = t.id AND c7.col2 = "val"
LEFT JOIN t2 c8 ON c8.parent_id = t.id AND c8.col2 = "val"
LEFT JOIN t2 c9 ON c9.parent_id = t.id AND c9.col2 = "val"
LEFT JOIN t2 c10 ON c10.parent_id = t.id AND c10.col2 = "val"
LEFT JOIN t2 c11 ON c11.parent_id = t.id AND c11.col2 = "val"
LEFT JOIN t2 c12 ON c12.parent_id = t.id AND c12.col2 = "val"
LEFT JOIN t2 c13 ON c13.parent_id = t.id AND c13.col2 = "val"
LEFT JOIN t2 c14 ON c14.parent_id = t.id AND c14.col2 = "val"
LEFT JOIN t2 c15 ON c15.parent_id = t.id AND c15.col2 = "val"
LEFT JOIN t2 c16 ON c16.parent_id = t.id AND c16.col2 = "val"
LEFT JOIN t2 c17 ON c17.parent_id = t.id AND c17.col2 = "val"
LEFT JOIN t2 c18 ON c18.parent_id = t.id AND c18.col2 = "val"
LEFT JOIN t2 c19 ON c19.parent_id = t.id AND c19.col2 = "val"
LEFT JOIN t2 c20 ON c20.parent_id = t.id AND c20.col2 = "val"
LEFT JOIN t2 c21 ON c21.parent_id = t.id AND c21.col2 = "val"
LEFT JOIN t2 c22 ON c22.parent_id = t.id AND c22.col2 = "val"
LEFT JOIN t2 c23 ON c23.parent_id = t.id AND c23.col2 = "val"
LEFT JOIN t2 c24 ON c24.parent_id = t.id AND c24.col2 = "val"
LEFT JOIN t2 c25 ON c25.parent_id = t.id AND c25.col2 = "val"
ORDER BY
col1;
select timestampdiff(second, @init_time, now()) <= 1;
EXPLAIN
SELECT t.*
FROM
t1 t
LEFT JOIN t2 c1 ON c1.parent_id = t.id AND c1.col2 = "val"
LEFT JOIN t2 c2 ON c2.parent_id = t.id AND c2.col2 = "val"
LEFT JOIN t2 c3 ON c3.parent_id = t.id AND c3.col2 = "val"
LEFT JOIN t2 c4 ON c4.parent_id = t.id AND c4.col2 = "val"
LEFT JOIN t2 c5 ON c5.parent_id = t.id AND c5.col2 = "val"
LEFT JOIN t2 c6 ON c6.parent_id = t.id AND c6.col2 = "val"
LEFT JOIN t2 c7 ON c7.parent_id = t.id AND c7.col2 = "val"
LEFT JOIN t2 c8 ON c8.parent_id = t.id AND c8.col2 = "val"
LEFT JOIN t2 c9 ON c9.parent_id = t.id AND c9.col2 = "val"
LEFT JOIN t2 c10 ON c10.parent_id = t.id AND c10.col2 = "val"
LEFT JOIN t2 c11 ON c11.parent_id = t.id AND c11.col2 = "val"
LEFT JOIN t2 c12 ON c12.parent_id = t.id AND c12.col2 = "val"
LEFT JOIN t2 c13 ON c13.parent_id = t.id AND c13.col2 = "val"
LEFT JOIN t2 c14 ON c14.parent_id = t.id AND c14.col2 = "val"
LEFT JOIN t2 c15 ON c15.parent_id = t.id AND c15.col2 = "val"
LEFT JOIN t2 c16 ON c16.parent_id = t.id AND c16.col2 = "val"
LEFT JOIN t2 c17 ON c17.parent_id = t.id AND c17.col2 = "val"
LEFT JOIN t2 c18 ON c18.parent_id = t.id AND c18.col2 = "val"
LEFT JOIN t2 c19 ON c19.parent_id = t.id AND c19.col2 = "val"
LEFT JOIN t2 c20 ON c20.parent_id = t.id AND c20.col2 = "val"
LEFT JOIN t2 c21 ON c21.parent_id = t.id AND c21.col2 = "val"
LEFT JOIN t2 c22 ON c22.parent_id = t.id AND c22.col2 = "val"
LEFT JOIN t2 c23 ON c23.parent_id = t.id AND c23.col2 = "val"
LEFT JOIN t2 c24 ON c24.parent_id = t.id AND c24.col2 = "val"
LEFT JOIN t2 c25 ON c25.parent_id = t.id AND c25.col2 = "val"
ORDER BY
col1;
set join_buffer_size=default;
set join_cache_level = default;
DROP TABLE t1,t2;
# this must be the last command in the file # this must be the last command in the file
set @@optimizer_switch=@save_optimizer_switch; set @@optimizer_switch=@save_optimizer_switch;

2
sql/sql_join_cache.cc
View File

@ -2087,7 +2087,7 @@ enum_nested_loop_state JOIN_CACHE::join_records(bool skip_last)
goto finish; goto finish;
if (outer_join_first_inner) if (outer_join_first_inner)
{ {
if (next_cache) if (next_cache && join_tab != join_tab->last_inner)
{ {
/* /*
Ensure that all matches for outer records from join buffer are to be Ensure that all matches for outer records from join buffer are to be