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Fix for bug #26447: "ALTER TABLE .. ORDER" does not work with InnoDB

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and auto_increment keys

Problems: 
  1. ALTER TABLE ... ORDER BY... doesn't make sence if there's a 
     user-defined clustered index in the table.
  2. using a secondary index is slower than using a clustered one 
     for a table scan.

Fixes:
  1. raise a warning.
  2. use the clustered index.
This commit is contained in:
ramil/ram@mysql.com/ramil.myoffice.izhnet.ru
2007-11-07 19:59:58 +04:00
parent 6a15726fa6
commit dc8d3d0bec
6 changed files with 75 additions and 42 deletions
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21
mysql-test/r/innodb_mysql.result
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@ -352,13 +352,13 @@ EXPLAIN
SELECT COUNT(*) FROM t2 LEFT JOIN t1 ON t2.fkey = t1.id
WHERE t1.name LIKE 'A%';
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index PRIMARY,name name 23 NULL 3 Using where; Using index
1 SIMPLE t1 index PRIMARY,name PRIMARY 4 NULL 3 Using where
1 SIMPLE t2 ref fkey fkey 5 test.t1.id 1 Using where; Using index
EXPLAIN
SELECT COUNT(*) FROM t2 LEFT JOIN t1 ON t2.fkey = t1.id
WHERE t1.name LIKE 'A%' OR FALSE;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 index NULL fkey 5 NULL 5 Using index
1 SIMPLE t2 index NULL PRIMARY 4 NULL 5
1 SIMPLE t1 eq_ref PRIMARY PRIMARY 4 test.t2.fkey 1 Using where
DROP TABLE t1,t2;
CREATE TABLE t1 (
@ -1260,11 +1260,11 @@ select_type SIMPLE
table t1
type index
possible_keys NULL
key b
key_len 5
key PRIMARY
key_len 4
ref NULL
rows 3
Extra Using index; Using filesort
Extra Using filesort
SELECT * FROM t1 ORDER BY b ASC, a DESC;
a b
1 1
@ -1276,11 +1276,11 @@ select_type SIMPLE
table t1
type index
possible_keys NULL
key b
key_len 5
key PRIMARY
key_len 4
ref NULL
rows 3
Extra Using index; Using filesort
Extra Using filesort
SELECT * FROM t1 ORDER BY b DESC, a ASC;
a b
2 2
@ -1470,4 +1470,9 @@ t2 CREATE TABLE `t2` (
) ENGINE=InnoDB DEFAULT CHARSET=latin1
DROP TABLE t2;
DROP TABLE t1;
create table t1 (a int auto_increment primary key) engine=innodb;
alter table t1 order by a;
Warnings:
Warning 1105 ORDER BY ignored as there is a user-defined clustered index in the table 't1'
drop table t1;
End of 5.1 tests