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Additional tweak to fix for bug #10543, to prevent a change in

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behavior when extending fields that were fully part of a
multi-part key.
This commit is contained in:
jimw@mysql.com 2005-06-02 10:00:36 -07:00
parent ef9ef1f958
commit d147e69bb7
3 changed files with 42 additions and 0 deletions
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25
mysql-test/r/key.result
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@ -329,3 +329,28 @@ ERROR 42S21: Duplicate column name 'c1'
alter table t1 add key (c1,c1,c2);
ERROR 42S21: Duplicate column name 'c1'
drop table t1;
create table t1 (a varchar(10), b varchar(10), key(a(10),b(10)));
show create table t1;
Table Create Table
t1 CREATE TABLE `t1` (
`a` varchar(10) default NULL,
`b` varchar(10) default NULL,
KEY `a` (`a`,`b`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1
alter table t1 modify b varchar(20);
show create table t1;
Table Create Table
t1 CREATE TABLE `t1` (
`a` varchar(10) default NULL,
`b` varchar(20) default NULL,
KEY `a` (`a`,`b`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1
alter table t1 modify a varchar(20);
show create table t1;
Table Create Table
t1 CREATE TABLE `t1` (
`a` varchar(20) default NULL,
`b` varchar(20) default NULL,
KEY `a` (`a`,`b`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1
drop table t1;

13
mysql-test/t/key.test
View File

@ -324,3 +324,16 @@ alter table t1 add key (c1,c2,c1);
--error 1060
alter table t1 add key (c1,c1,c2);
drop table t1;
#
# If we use a partial field for a key that is actually the length of the
# field, and we extend the field, we end up with a key that includes the
# whole new length of the field.
#
create table t1 (a varchar(10), b varchar(10), key(a(10),b(10)));
show create table t1;
alter table t1 modify b varchar(20);
show create table t1;
alter table t1 modify a varchar(20);
show create table t1;
drop table t1;

4
sql/sql_table.cc
View File

@ -3341,11 +3341,15 @@ bool mysql_alter_table(THD *thd,char *new_db, char *new_name,
previous type, or the field length is less than the key part
length, unset the key part length.
We also unset the key part length if it is the same as the
old field's length, so the whole new field will be used.
BLOBs may have cfield->length == 0, which is why we test it before
checking whether cfield->length < key_part_length (in chars).
*/
if (!Field::type_can_have_key_part(cfield->field->type()) ||
!Field::type_can_have_key_part(cfield->sql_type) ||
cfield->field->field_length == key_part_length ||
(cfield->length && (cfield->length < key_part_length /
key_part->field->charset()->mbmaxlen)))
key_part_length= 0; // Use whole field