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WL#3527: Extend IGNORE INDEX so places where index is ignored

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can be specified
Currently MySQL allows one to specify what indexes to ignore during
join optimization. The scope of the current USE/FORCE/IGNORE INDEX 
statement is only the FROM clause, while all other clauses are not 
affected.

However, in certain cases, the optimizer
may incorrectly choose an index for sorting and/or grouping, and
produce an inefficient query plan.

This task provides the means to specify what indexes are
ignored/used for what operation in a more fine-grained manner, thus
making it possible to manually force a better plan. We do this
by extending the current IGNORE/USE/FORCE INDEX syntax to:

IGNORE/USE/FORCE INDEX [FOR {JOIN | ORDER | GROUP BY}]

so that:
- if no FOR is specified, the index hint will apply everywhere.
- if MySQL is started with the compatibility option --old_mode then
  an index hint without a FOR clause works as in 5.0 (i.e, the 
  index will only be ignored for JOINs, but can still be used to
  compute ORDER BY).

See the WL#3527 for further details.
This commit is contained in:
gkodinov/kgeorge@macbook.gmz
2007-03-05 19:08:41 +02:00
parent 6a49f0cd93
commit b9c82eaa89
25 changed files with 727 additions and 458 deletions
Download Patch File Download Diff File Expand all files Collapse all files

15
mysql-test/r/endspace.result
View File

@ -25,10 +25,11 @@ insert into t1 values ('teststring'), ('nothing'), ('teststring\t');
check table t1;
Table Op Msg_type Msg_text
test.t1 check status OK
select * from t1 ignore key (key1) where text1='teststring' or text1 like 'teststring_%';
select * from t1 ignore key (key1) where text1='teststring' or
text1 like 'teststring_%' ORDER BY text1;
text1
teststring
teststring
teststring
select * from t1 where text1='teststring' or text1 like 'teststring_%';
text1
teststring
@ -48,10 +49,11 @@ alter table t1 modify text1 char(32) binary not null;
check table t1;
Table Op Msg_type Msg_text
test.t1 check status OK
select * from t1 ignore key (key1) where text1='teststring' or text1 like 'teststring_%';
select * from t1 ignore key (key1) where text1='teststring' or
text1 like 'teststring_%' ORDER BY text1;
text1
teststring
teststring
teststring
select concat('|', text1, '|') from t1 where text1='teststring' or text1 like 'teststring_%';
concat('|', text1, '|')
|teststring |
@ -132,10 +134,11 @@ concat('|', text1, '|')
drop table t1;
create table t1 (text1 varchar(32) not NULL, KEY key1 using BTREE (text1)) engine=heap;
insert into t1 values ('teststring'), ('nothing'), ('teststring\t');
select * from t1 ignore key (key1) where text1='teststring' or text1 like 'teststring_%';
select * from t1 ignore key (key1) where text1='teststring' or
text1 like 'teststring_%' ORDER BY text1;
text1
teststring
teststring
teststring
select * from t1 where text1='teststring' or text1 like 'teststring_%';
text1
teststring

112
mysql-test/r/group_by.result
View File

@ -933,12 +933,110 @@ b sum(1)
18 6
19 6
DROP TABLE t1;
CREATE TABLE t1 (a INT, b INT, KEY(a));
INSERT INTO t1 VALUES (1, 1), (2, 2), (3,3), (4,4);
EXPLAIN SELECT a, SUM(b) FROM t1 GROUP BY a LIMIT 2;
CREATE TABLE t1 (a INT, b INT,
PRIMARY KEY (a),
KEY i2(a,b));
INSERT INTO t1 VALUES (1,1),(2,2),(3,3),(4,4),(5,5),(6,6),(7,7),(8,8);
INSERT INTO t1 SELECT a + 8,b FROM t1;
INSERT INTO t1 SELECT a + 16,b FROM t1;
INSERT INTO t1 SELECT a + 32,b FROM t1;
INSERT INTO t1 SELECT a + 64,b FROM t1;
INSERT INTO t1 SELECT a + 128,b FROM t1;
ANALYZE TABLE t1;
Table Op Msg_type Msg_text
test.t1 analyze status OK
EXPLAIN SELECT a FROM t1 WHERE a < 2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index NULL a 5 NULL 4
EXPLAIN SELECT a, SUM(b) FROM t1 IGNORE INDEX (a) GROUP BY a LIMIT 2;
1 SIMPLE t1 range PRIMARY,i2 PRIMARY 4 NULL 2 Using where; Using index
EXPLAIN SELECT a FROM t1 WHERE a < 2 ORDER BY a;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 4 Using temporary; Using filesort
DROP TABLE t1;
1 SIMPLE t1 range PRIMARY,i2 PRIMARY 4 NULL 2 Using where; Using index
EXPLAIN SELECT a FROM t1 WHERE a < 2 GROUP BY a;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range PRIMARY,i2 PRIMARY 4 NULL 2 Using where; Using index
EXPLAIN SELECT a FROM t1 IGNORE INDEX (PRIMARY,i2);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 256
EXPLAIN SELECT a FROM t1 IGNORE INDEX FOR JOIN (PRIMARY,i2);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 256
EXPLAIN SELECT a FROM t1 IGNORE INDEX FOR GROUP BY (PRIMARY,i2) GROUP BY a;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index NULL PRIMARY 4 NULL 256 Using index
EXPLAIN SELECT a FROM t1 IGNORE INDEX FOR ORDER BY (PRIMARY,i2) ORDER BY a;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index NULL PRIMARY 4 NULL 256 Using index
EXPLAIN SELECT a FROM t1 IGNORE INDEX FOR ORDER BY (PRIMARY)
IGNORE INDEX FOR GROUP BY (i2) GROUP BY a;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index NULL PRIMARY 4 NULL 256 Using index
EXPLAIN SELECT a FROM t1 IGNORE INDEX (PRIMARY) IGNORE INDEX FOR ORDER BY (i2);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index NULL i2 9 NULL 256 Using index
EXPLAIN SELECT a FROM t1 FORCE INDEX (i2);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index NULL i2 9 NULL 256 Using index
EXPLAIN SELECT a FROM t1 USE INDEX ();
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 256
EXPLAIN SELECT a FROM t1 USE INDEX () USE INDEX (i2);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 256
EXPLAIN SELECT a FROM t1
FORCE INDEX (PRIMARY)
IGNORE INDEX FOR GROUP BY (i2)
IGNORE INDEX FOR ORDER BY (i2)
USE INDEX (i2);
ERROR HY000: Incorrect usage of USE INDEX and FORCE INDEX
EXPLAIN SELECT a FROM t1 USE INDEX (i2) USE INDEX ();
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index NULL i2 9 NULL 256 Using index
EXPLAIN SELECT a FROM t1 FORCE INDEX ();
ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ')' at line 1
EXPLAIN SELECT a FROM t1 IGNORE INDEX ();
ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ')' at line 1
EXPLAIN SELECT a FROM t1 USE INDEX FOR JOIN (i2)
USE INDEX FOR GROUP BY (i2) GROUP BY a;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index NULL i2 9 NULL 256 Using index
EXPLAIN SELECT a FROM t1 FORCE INDEX FOR JOIN (i2)
FORCE INDEX FOR GROUP BY (i2) GROUP BY a;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range NULL i2 4 NULL 257 Using index for group-by
EXPLAIN SELECT a FROM t1 USE INDEX () IGNORE INDEX (i2);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 256
EXPLAIN SELECT a FROM t1 IGNORE INDEX (i2) USE INDEX ();
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 256
EXPLAIN SELECT a FROM t1
USE INDEX FOR GROUP BY (i2)
USE INDEX FOR ORDER BY (i2)
USE INDEX FOR JOIN (i2);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index NULL i2 9 NULL 256 Using index
EXPLAIN SELECT a FROM t1
USE INDEX FOR JOIN (i2)
USE INDEX FOR JOIN (i2)
USE INDEX FOR JOIN (i2,i2);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index NULL i2 9 NULL 256 Using index
EXPLAIN SELECT 1 FROM t1 WHERE a IN
(SELECT a FROM t1 USE INDEX (i2) IGNORE INDEX (i2));
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 index NULL PRIMARY 4 NULL 256 Using where; Using index
2 DEPENDENT SUBQUERY t1 ALL NULL NULL NULL NULL 256 Using where
CREATE TABLE t2 (a INT, b INT, KEY(a));
INSERT INTO t2 VALUES (1, 1), (2, 2), (3,3), (4,4);
EXPLAIN SELECT a, SUM(b) FROM t2 GROUP BY a LIMIT 2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 index NULL a 5 NULL 4
EXPLAIN SELECT a, SUM(b) FROM t2 IGNORE INDEX (a) GROUP BY a LIMIT 2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 ALL NULL NULL NULL NULL 4 Using temporary; Using filesort
EXPLAIN SELECT 1 FROM t2 WHERE a IN
(SELECT a FROM t1 USE INDEX (i2) IGNORE INDEX (i2));
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t2 index NULL a 5 NULL 4 Using where; Using index
2 DEPENDENT SUBQUERY t1 ALL NULL NULL NULL NULL 256 Using where
DROP TABLE t1, t2;

9
mysql-test/t/endspace.test
View File

@ -16,7 +16,8 @@ drop table if exists t1;
create table t1 (text1 varchar(32) not NULL, KEY key1 (text1));
insert into t1 values ('teststring'), ('nothing'), ('teststring\t');
check table t1;
select * from t1 ignore key (key1) where text1='teststring' or text1 like 'teststring_%';
select * from t1 ignore key (key1) where text1='teststring' or
text1 like 'teststring_%' ORDER BY text1;
select * from t1 where text1='teststring' or text1 like 'teststring_%';
select * from t1 where text1='teststring' or text1 > 'teststring\t';
select * from t1 order by text1;
@ -24,7 +25,8 @@ explain select * from t1 order by text1;
alter table t1 modify text1 char(32) binary not null;
check table t1;
select * from t1 ignore key (key1) where text1='teststring' or text1 like 'teststring_%';
select * from t1 ignore key (key1) where text1='teststring' or
text1 like 'teststring_%' ORDER BY text1;
select concat('|', text1, '|') from t1 where text1='teststring' or text1 like 'teststring_%';
select concat('|', text1, '|') from t1 where text1='teststring' or text1 > 'teststring\t';
select text1, length(text1) from t1 order by text1;
@ -57,7 +59,8 @@ drop table t1;
create table t1 (text1 varchar(32) not NULL, KEY key1 using BTREE (text1)) engine=heap;
insert into t1 values ('teststring'), ('nothing'), ('teststring\t');
select * from t1 ignore key (key1) where text1='teststring' or text1 like 'teststring_%';
select * from t1 ignore key (key1) where text1='teststring' or
text1 like 'teststring_%' ORDER BY text1;
select * from t1 where text1='teststring' or text1 like 'teststring_%';
select * from t1 where text1='teststring' or text1 >= 'teststring\t';
select * from t1 order by text1;

66
mysql-test/t/group_by.test
View File

@ -706,10 +706,66 @@ DROP TABLE t1;
# Bug #21174: Index degrades sort performance and
# optimizer does not honor IGNORE INDEX
#
CREATE TABLE t1 (a INT, b INT, KEY(a));
INSERT INTO t1 VALUES (1, 1), (2, 2), (3,3), (4,4);
CREATE TABLE t1 (a INT, b INT,
PRIMARY KEY (a),
KEY i2(a,b));
INSERT INTO t1 VALUES (1,1),(2,2),(3,3),(4,4),(5,5),(6,6),(7,7),(8,8);
INSERT INTO t1 SELECT a + 8,b FROM t1;
INSERT INTO t1 SELECT a + 16,b FROM t1;
INSERT INTO t1 SELECT a + 32,b FROM t1;
INSERT INTO t1 SELECT a + 64,b FROM t1;
INSERT INTO t1 SELECT a + 128,b FROM t1;
ANALYZE TABLE t1;
EXPLAIN SELECT a FROM t1 WHERE a < 2;
EXPLAIN SELECT a FROM t1 WHERE a < 2 ORDER BY a;
EXPLAIN SELECT a FROM t1 WHERE a < 2 GROUP BY a;
EXPLAIN SELECT a FROM t1 IGNORE INDEX (PRIMARY,i2);
EXPLAIN SELECT a FROM t1 IGNORE INDEX FOR JOIN (PRIMARY,i2);
EXPLAIN SELECT a FROM t1 IGNORE INDEX FOR GROUP BY (PRIMARY,i2) GROUP BY a;
EXPLAIN SELECT a FROM t1 IGNORE INDEX FOR ORDER BY (PRIMARY,i2) ORDER BY a;
EXPLAIN SELECT a FROM t1 IGNORE INDEX FOR ORDER BY (PRIMARY)
IGNORE INDEX FOR GROUP BY (i2) GROUP BY a;
EXPLAIN SELECT a FROM t1 IGNORE INDEX (PRIMARY) IGNORE INDEX FOR ORDER BY (i2);
EXPLAIN SELECT a FROM t1 FORCE INDEX (i2);
EXPLAIN SELECT a FROM t1 USE INDEX ();
EXPLAIN SELECT a FROM t1 USE INDEX () USE INDEX (i2);
--error ER_WRONG_USAGE
EXPLAIN SELECT a FROM t1
FORCE INDEX (PRIMARY)
IGNORE INDEX FOR GROUP BY (i2)
IGNORE INDEX FOR ORDER BY (i2)
USE INDEX (i2);
EXPLAIN SELECT a FROM t1 USE INDEX (i2) USE INDEX ();
--error ER_PARSE_ERROR
EXPLAIN SELECT a FROM t1 FORCE INDEX ();
--error ER_PARSE_ERROR
EXPLAIN SELECT a FROM t1 IGNORE INDEX ();
EXPLAIN SELECT a FROM t1 USE INDEX FOR JOIN (i2)
USE INDEX FOR GROUP BY (i2) GROUP BY a;
EXPLAIN SELECT a FROM t1 FORCE INDEX FOR JOIN (i2)
FORCE INDEX FOR GROUP BY (i2) GROUP BY a;
EXPLAIN SELECT a FROM t1 USE INDEX () IGNORE INDEX (i2);
EXPLAIN SELECT a FROM t1 IGNORE INDEX (i2) USE INDEX ();
EXPLAIN SELECT a, SUM(b) FROM t1 GROUP BY a LIMIT 2;
EXPLAIN SELECT a, SUM(b) FROM t1 IGNORE INDEX (a) GROUP BY a LIMIT 2;
EXPLAIN SELECT a FROM t1
USE INDEX FOR GROUP BY (i2)
USE INDEX FOR ORDER BY (i2)
USE INDEX FOR JOIN (i2);
DROP TABLE t1;
EXPLAIN SELECT a FROM t1
USE INDEX FOR JOIN (i2)
USE INDEX FOR JOIN (i2)
USE INDEX FOR JOIN (i2,i2);
EXPLAIN SELECT 1 FROM t1 WHERE a IN
(SELECT a FROM t1 USE INDEX (i2) IGNORE INDEX (i2));
CREATE TABLE t2 (a INT, b INT, KEY(a));
INSERT INTO t2 VALUES (1, 1), (2, 2), (3,3), (4,4);
EXPLAIN SELECT a, SUM(b) FROM t2 GROUP BY a LIMIT 2;
EXPLAIN SELECT a, SUM(b) FROM t2 IGNORE INDEX (a) GROUP BY a LIMIT 2;
EXPLAIN SELECT 1 FROM t2 WHERE a IN
(SELECT a FROM t1 USE INDEX (i2) IGNORE INDEX (i2));
DROP TABLE t1, t2;