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072073c09e
The patch differs from the original MySQL patch as follows:
- All test case differences have been reviewed one by one, and
care has been taken to restore the original plan so that each
test case executes the code path it was designed for.
- A bug was found and fixed in MariaDB 5.3 in
Item_allany_subselect::cleanup().
- ORDER BY is not removed because we are unsure of all effects,
and it would prevent enabling ORDER BY ... LIMIT subqueries.
- ref_pointer_array.m_size is not adjusted because we don't do
array bounds checking, and because it looks risky.
Original comment by Jorgen Loland:
-------------------------------------------------------------
WL#5953 - Optimize away useless subquery clauses
For IN/ALL/ANY/SOME/EXISTS subqueries, the following clauses are
meaningless:
* ORDER BY (since we don't support LIMIT in these subqueries)
* DISTINCT
* GROUP BY if there is no HAVING clause and no aggregate
functions
This WL detects and optimizes away these useless parts of the
query during JOIN::prepare()
113 lines
3.1 KiB
Text
113 lines
3.1 KiB
Text
#
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# Run subselect_sj2.test with BKA enabled
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#
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set @save_optimizer_switch_jcl6=@@optimizer_switch;
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set @@optimizer_switch='optimize_join_buffer_size=on';
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set @@optimizer_switch='semijoin_with_cache=on';
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set @@optimizer_switch='outer_join_with_cache=on';
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set optimizer_switch='mrr=on,mrr_sort_keys=on,index_condition_pushdown=on';
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set join_cache_level=6;
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show variables like 'join_cache_level';
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set @optimizer_switch_for_subselect_sj2_test=@@optimizer_switch;
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set @join_cache_level_for_subselect_sj2_test=@@join_cache_level;
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--source t/subselect_sj2.test
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--echo #
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--echo # Bug #898073: potential incremental join cache for semijoin
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--echo #
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CREATE TABLE t1 (a int, b varchar(1), KEY (b,a));
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INSERT INTO t1 VALUES (0,'x'), (5,'r');
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CREATE TABLE t2 (a int) ENGINE=InnoDB;
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INSERT INTO t2 VALUES (8);
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CREATE TABLE t3 (b varchar(1), c varchar(1)) ENGINE=InnoDB;
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INSERT INTO t3 VALUES ('x','x');
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CREATE TABLE t4 (a int NOT NULL, b varchar(1)) ENGINE=InnoDB;
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INSERT INTO t4 VALUES (20,'r'), (10,'x');
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set @tmp_optimizer_switch=@@optimizer_switch;
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SET SESSION optimizer_switch='semijoin_with_cache=on';
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SET SESSION join_cache_level=2;
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EXPLAIN
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SELECT t3.* FROM t1 JOIN t3 ON t3.b = t1.b
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WHERE c IN (SELECT t4.b FROM t4 JOIN t2);
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SELECT t3.* FROM t1 JOIN t3 ON t3.b = t1.b
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WHERE c IN (SELECT t4.b FROM t4 JOIN t2);
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set optimizer_switch=@tmp_optimizer_switch;
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set join_cache_level=default;
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DROP TABLE t1,t2,t3,t4;
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--echo #
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--echo # Bug #899696: potential incremental join cache for semijoin
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--echo #
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CREATE TABLE t1 (pk int PRIMARY KEY, a int);
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INSERT INTO t1 VALUES (1, 6), (2, 8);
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CREATE TABLE t2 (b int) ENGINE=InnoDB;
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INSERT INTO t2 VALUES (8);
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CREATE TABLE t3 (pk int PRIMARY KEY, a int);
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INSERT INTO t3 VALUES (1, 6), (2, 8);
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CREATE TABLE t4 (b int) ENGINE=InnoDB;
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INSERT INTO t4 VALUES (2);
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set @tmp_optimizer_switch=@@optimizer_switch;
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SET optimizer_switch = 'semijoin_with_cache=on';
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SET join_cache_level = 2;
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EXPLAIN
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SELECT * FROM t1, t2 WHERE b IN (SELECT a FROM t3, t4 WHERE b = pk);
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SELECT * FROM t1, t2 WHERE b IN (SELECT a FROM t3, t4 WHERE b = pk);
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set optimizer_switch=@tmp_optimizer_switch;
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set join_cache_level=default;
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DROP TABLE t1,t2,t3,t4;
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--echo #
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--echo # Bug #899962: materialized subquery with join_cache_level=3
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--echo #
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CREATE TABLE t1 (a varchar(1), b varchar(1)) ENGINE=InnoDB;
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INSERT INTO t1 VALUES ('v','v');
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CREATE TABLE t2 (a varchar(1), b varchar(1)) ENGINE=InnoDB;
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INSERT INTO t2 VALUES ('v','v');
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set @tmp_optimizer_switch=@@optimizer_switch;
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SET optimizer_switch = 'semijoin_with_cache=on';
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SET join_cache_level = 3;
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EXPLAIN
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SELECT * FROM t1 WHERE b IN (SELECT a FROM t2 GROUP BY a);
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SELECT * FROM t1 WHERE b IN (SELECT a FROM t2 GROUP BY a);
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EXPLAIN
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SELECT * FROM t1 WHERE b IN (SELECT max(a) FROM t2 GROUP BY a);
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SELECT * FROM t1 WHERE b IN (SELECT max(a) FROM t2 GROUP BY a);
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set optimizer_switch=@tmp_optimizer_switch;
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set join_cache_level=default;
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DROP TABLE t1,t2;
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set join_cache_level=default;
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show variables like 'join_cache_level';
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set @@optimizer_switch=@save_optimizer_switch_jcl6;
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set @optimizer_switch_for_subselect_sj2_test=NULL;
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set @join_cache_level_subselect_sj2_test=NULL;
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