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