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Optimization of key usage (ORDER BY) (SCRUM)

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2003-01-04 14:59:52 +04:00
parent a533a95c28
commit 24b256987e
3 changed files with 139 additions and 0 deletions
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34
mysql-test/r/order_by.result
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@ -506,3 +506,37 @@ SELECT titre,t1.numeropost,auteur,icone,nbrep,'0',date,vue,ouvert,lastauteur,des
titre numeropost auteur icone nbrep 0 date vue ouvert lastauteur dest
test 1 joce 0 0 0 0000-00-00 00:00:00 0 1 bug
drop table t1,t2;
CREATE TABLE t1 (
FieldKey varchar(36) NOT NULL default '',
LongVal bigint(20) default NULL,
StringVal mediumtext,
KEY FieldKey (FieldKey),
KEY LongField (FieldKey,LongVal),
KEY StringField (FieldKey,StringVal(32))
);
INSERT INTO t1 VALUES ('0',3,'0'),('1',2,'1'),('1',1,'3'), ('1',0,'2');
EXPLAIN SELECT * FROM t1 WHERE FieldKey = '1' ORDER BY LongVal;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref FieldKey,LongField,StringField LongField 36 const 2 Using where
SELECT * FROM t1 WHERE FieldKey = '1' ORDER BY LongVal;
FieldKey LongVal StringVal
1 0 2
1 1 3
1 2 1
EXPLAIN SELECT * FROM t1 WHERE FieldKey > '0' ORDER BY LongVal;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range FieldKey,LongField,StringField FieldKey 36 NULL 3 Using where; Using filesort
SELECT * FROM t1 WHERE FieldKey > '0' ORDER BY LongVal;
FieldKey LongVal StringVal
1 0 2
1 1 3
1 2 1
EXPLAIN SELECT * FROM t1 WHERE FieldKey > '0' ORDER BY FieldKey, LongVal;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range FieldKey,LongField,StringField LongField 36 NULL 3 Using where
SELECT * FROM t1 WHERE FieldKey > '0' ORDER BY FieldKey, LongVal;
FieldKey LongVal StringVal
1 0 2
1 1 3
1 2 1
DROP TABLE t1;