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Bug #30596 GROUP BY optimization gives wrong result order

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The optimization that uses a unique index to remove GROUP BY, did not 
ensure that the index was actually used, thus violating the ORDER BY
that is impled by GROUP BY.
Fixed by replacing GROUP BY with ORDER BY if the GROUP BY clause contains
a unique index. In case GROUP BY ... ORDER BY null is used, GROUP BY is
simply removed.


BitKeeper/etc/ignore:
  Added support-files/mysqld_multi.server tests/bug25714 cscope.in.out cscope.out cscope.po.out to the ignore list
mysql-test/r/distinct.result:
  Bug#30596: Changed test case. 
  Prior to Bug#16458, These queries use temp table and filesort. The
  bug was that they used a temp table. However, that patch removed
  filesort also, in which case we can no longer gurantee correct ordering.
mysql-test/r/group_by.result:
  Bug#30596: Correct result
mysql-test/r/innodb_mysql.result:
  Bug#30596: Test case for innodb. Here, as opposed to for MyISAM, row 
  lookup is done using index whenever the index covers the group list.
mysql-test/t/group_by.test:
  Bug#30596: Test case
mysql-test/t/innodb_mysql.test:
  Bug#30596: Test case
sql/sql_select.cc:
  Bug#30596: The fix, replacing GROUP BY with ORDER BY unless 
  ORDER BY [NULL|<constant>]
This commit is contained in:
unknown
2007-08-27 17:33:41 +02:00
parent de619bd17c
commit 2368664681
7 changed files with 168 additions and 3 deletions
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49
mysql-test/r/innodb_mysql.result
View File

@ -1047,4 +1047,53 @@ t1 CREATE TABLE `t1` (
KEY `a` (`a`(255))
) ENGINE=InnoDB DEFAULT CHARSET=utf8
drop table t1;
CREATE TABLE t1(
a INT,
b INT NOT NULL,
c INT NOT NULL,
d INT,
UNIQUE KEY (c,b)
) engine=innodb;
INSERT INTO t1 VALUES (1,1,1,50), (1,2,3,40), (2,1,3,4);
EXPLAIN SELECT c,b,d FROM t1 GROUP BY c,b,d;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 3 Using filesort
SELECT c,b,d FROM t1 GROUP BY c,b,d;
c b d
1 1 50
3 1 4
3 2 40
EXPLAIN SELECT c,b,d FROM t1 GROUP BY c,b,d ORDER BY NULL;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 3
SELECT c,b,d FROM t1 GROUP BY c,b,d ORDER BY NULL;
c b d
1 1 50
3 1 4
3 2 40
EXPLAIN SELECT c,b,d FROM t1 ORDER BY c,b,d;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 3 Using filesort
SELECT c,b,d FROM t1 ORDER BY c,b,d;
c b d
1 1 50
3 1 4
3 2 40
EXPLAIN SELECT c,b,d FROM t1 GROUP BY c,b;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index NULL c 8 NULL 3
SELECT c,b,d FROM t1 GROUP BY c,b;
c b d
1 1 50
3 1 4
3 2 40
EXPLAIN SELECT c,b FROM t1 GROUP BY c,b;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index NULL c 8 NULL 3 Using index
SELECT c,b FROM t1 GROUP BY c,b;
c b
1 1
3 1
3 2
DROP TABLE t1;
End of 5.0 tests