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MDEV-465: Optimizer : wrong index choice: Add a testcase.

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This commit is contained in:
Sergei Petrunia
2014-09-09 13:26:23 +04:00
parent 8bd4716272
commit bf30585eaf
2 changed files with 75 additions and 0 deletions
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36
mysql-test/r/order_by.result
View File

@@ -2949,3 +2949,39 @@ explain update t1 set key1=key1+1 where key1 between 10 and 110 order by key1 li
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range key1 key1 5 NULL 2 Using where; Using buffer
drop table t1,t2;
#
# MDEV-465: Optimizer : wrong index choice, leading to strong performances issues
#
CREATE TABLE t1 (
id1 int(10) unsigned NOT NULL auto_increment,
id2 tinyint(3) unsigned NOT NULL default '0',
id3 tinyint(3) unsigned NOT NULL default '0',
id4 int(10) unsigned NOT NULL default '0',
date timestamp NOT NULL default CURRENT_TIMESTAMP,
PRIMARY KEY (id1),
KEY id_234_date (id2,id3,id4,date),
KEY id_23_date (id2,id3,date)
) ENGINE=MyISAM DEFAULT CHARSET=latin1;
# t1 has "bad" index declaration order..
CREATE TABLE t2 (
id1 int(10) unsigned NOT NULL auto_increment,
id2 tinyint(3) unsigned NOT NULL default '0',
id3 tinyint(3) unsigned NOT NULL default '0',
id4 int(10) unsigned NOT NULL default '0',
date timestamp NOT NULL default CURRENT_TIMESTAMP,
PRIMARY KEY (id1),
KEY id_23_date (id2,id3,date),
KEY id_234_date (id2,id3,id4,date)
) ENGINE=MyISAM DEFAULT CHARSET=latin1;
# t2 has a "good" index declaration order
INSERT INTO t1 (id2,id3,id4) VALUES (1,1,1),(1,1,1),(1,1,1),(1,1,1),(1,0,1),(1,2,1),(1,3,1);
INSERT INTO t2 (id2,id3,id4) VALUES (1,1,1),(1,1,1),(1,1,1),(1,1,1),(1,0,1),(1,2,1),(1,3,1);
# The following two must both use id_23_date and no "using filesort":
EXPLAIN SELECT id1 FROM t1 WHERE id2=1 AND id3=1 ORDER BY date DESC LIMIT 0,4;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range id_234_date,id_23_date id_23_date 2 NULL 3 Using where
# See above query
EXPLAIN SELECT id1 FROM t2 WHERE id2=1 AND id3=1 ORDER BY date DESC LIMIT 0,4;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 ref id_23_date,id_234_date id_23_date 2 const,const 3 Using where
drop table t1,t2;

39
mysql-test/t/order_by.test
View File

@@ -1958,3 +1958,42 @@ select A.a + 10 * B.a + 100 * C.a, 1234 from t2 A, t2 B, t2 C;
--echo # Should show rows=2, not rows=100
explain update t1 set key1=key1+1 where key1 between 10 and 110 order by key1 limit 2;
drop table t1,t2;
--echo #
--echo # MDEV-465: Optimizer : wrong index choice, leading to strong performances issues
--echo #
CREATE TABLE t1 (
id1 int(10) unsigned NOT NULL auto_increment,
id2 tinyint(3) unsigned NOT NULL default '0',
id3 tinyint(3) unsigned NOT NULL default '0',
id4 int(10) unsigned NOT NULL default '0',
date timestamp NOT NULL default CURRENT_TIMESTAMP,
PRIMARY KEY (id1),
KEY id_234_date (id2,id3,id4,date),
KEY id_23_date (id2,id3,date)
) ENGINE=MyISAM DEFAULT CHARSET=latin1;
--echo # t1 has "bad" index declaration order..
CREATE TABLE t2 (
id1 int(10) unsigned NOT NULL auto_increment,
id2 tinyint(3) unsigned NOT NULL default '0',
id3 tinyint(3) unsigned NOT NULL default '0',
id4 int(10) unsigned NOT NULL default '0',
date timestamp NOT NULL default CURRENT_TIMESTAMP,
PRIMARY KEY (id1),
KEY id_23_date (id2,id3,date),
KEY id_234_date (id2,id3,id4,date)
) ENGINE=MyISAM DEFAULT CHARSET=latin1;
--echo # t2 has a "good" index declaration order
INSERT INTO t1 (id2,id3,id4) VALUES (1,1,1),(1,1,1),(1,1,1),(1,1,1),(1,0,1),(1,2,1),(1,3,1);
INSERT INTO t2 (id2,id3,id4) VALUES (1,1,1),(1,1,1),(1,1,1),(1,1,1),(1,0,1),(1,2,1),(1,3,1);
--echo # The following two must both use id_23_date and no "using filesort":
EXPLAIN SELECT id1 FROM t1 WHERE id2=1 AND id3=1 ORDER BY date DESC LIMIT 0,4;
--echo # See above query
EXPLAIN SELECT id1 FROM t2 WHERE id2=1 AND id3=1 ORDER BY date DESC LIMIT 0,4;
drop table t1,t2;