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Change the default @@optimizer_switch settings:

- semijoin=on
- firstmatch=on
- loosescan=on
This commit is contained in:
Sergey Petrunya
2011-11-02 13:48:41 +04:00
parent 6498687325
commit 47861a6577
18 changed files with 861 additions and 98 deletions

View File

@ -199,16 +199,16 @@ insert into t2 values ('2001-01-01 1:1:1'), ('2001-01-01 1:1:1');
flush tables;
EXPLAIN SELECT OUTR.dt FROM t1 AS OUTR WHERE OUTR.dt IN (SELECT INNR.dt FROM t2 AS INNR WHERE OUTR.dt IS NULL );
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY OUTR ALL NULL NULL NULL NULL 2 Using where
2 DEPENDENT SUBQUERY INNR ALL NULL NULL NULL NULL 2 Using where
1 PRIMARY OUTR ALL NULL NULL NULL NULL 2 Using where; Start temporary
1 PRIMARY INNR ALL NULL NULL NULL NULL 2 Using where; End temporary; Using join buffer (flat, BNL join)
flush tables;
SELECT OUTR.dt FROM t1 AS OUTR WHERE OUTR.dt IN (SELECT INNR.dt FROM t2 AS INNR WHERE OUTR.dt IS NULL );
dt
flush tables;
EXPLAIN SELECT OUTR.dt FROM t1 AS OUTR WHERE OUTR.dt IN ( SELECT INNR.dt FROM t2 AS INNR WHERE OUTR.t < '2005-11-13 7:41:31' );
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY OUTR ALL NULL NULL NULL NULL 2 Using where
2 DEPENDENT SUBQUERY INNR ALL NULL NULL NULL NULL 2 Using where
1 PRIMARY OUTR ALL NULL NULL NULL NULL 2 Using where; Start temporary
1 PRIMARY INNR ALL NULL NULL NULL NULL 2 Using where; End temporary; Using join buffer (flat, BNL join)
flush tables;
SELECT OUTR.dt FROM t1 AS OUTR WHERE OUTR.dt IN ( SELECT INNR.dt FROM t2 AS INNR WHERE OUTR.t < '2005-11-13 7:41:31' );
dt