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Fix partial keys when converting VARCHAR to TEXT. (Bug #10543)

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This commit is contained in:
jimw@mysql.com 2005-05-25 18:11:47 -07:00
parent b763679f1c
commit ef9ef1f958
5 changed files with 84 additions and 6 deletions
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23
mysql-test/r/type_varchar.result
View file

@ -392,3 +392,26 @@ group by t1.b, t1.a;
a b min(t1.b)
22 NULL NULL
drop table t1, t2;
create table t1 (f1 varchar(65500));
create index index1 on t1(f1(10));
show create table t1;
Table Create Table
t1 CREATE TABLE `t1` (
`f1` varchar(65500) default NULL,
KEY `index1` (`f1`(10))
) ENGINE=MyISAM DEFAULT CHARSET=latin1
alter table t1 modify f1 varchar(255);
show create table t1;
Table Create Table
t1 CREATE TABLE `t1` (
`f1` varchar(255) default NULL,
KEY `index1` (`f1`(10))
) ENGINE=MyISAM DEFAULT CHARSET=latin1
alter table t1 modify f1 tinytext;
show create table t1;
Table Create Table
t1 CREATE TABLE `t1` (
`f1` tinytext,
KEY `index1` (`f1`(10))
) ENGINE=MyISAM DEFAULT CHARSET=latin1
drop table t1;

12
mysql-test/t/type_varchar.test
View file

@ -118,3 +118,15 @@ insert into t2 values (22), (22);
select t1.a, t1.b, min(t1.b) from t1 inner join t2 ON t2.a = t1.a
group by t1.b, t1.a;
drop table t1, t2;
#
# Bug #10543: convert varchar with index to text
#
create table t1 (f1 varchar(65500));
create index index1 on t1(f1(10));
show create table t1;
alter table t1 modify f1 varchar(255);
show create table t1;
alter table t1 modify f1 tinytext;
show create table t1;
drop table t1;

33
sql/field.cc
View file

@ -982,6 +982,39 @@ Item_result Field::result_merge_type(enum_field_types field_type)
Static help functions
*****************************************************************************/
/*
Check whether a field type can be partially indexed by a key
This is a static method, rather than a virtual function, because we need
to check the type of a non-Field in mysql_alter_table().
SYNOPSIS
type_can_have_key_part()
type field type
RETURN
TRUE Type can have a prefixed key
FALSE Type can not have a prefixed key
*/
bool Field::type_can_have_key_part(enum enum_field_types type)
{
switch (type) {
case MYSQL_TYPE_VARCHAR:
case MYSQL_TYPE_TINY_BLOB:
case MYSQL_TYPE_MEDIUM_BLOB:
case MYSQL_TYPE_LONG_BLOB:
case MYSQL_TYPE_BLOB:
case MYSQL_TYPE_VAR_STRING:
case MYSQL_TYPE_STRING:
return TRUE;
default:
return FALSE;
}
}
/*
Numeric fields base class constructor
*/

1
sql/field.h
View file

@ -119,6 +119,7 @@ public:
virtual Item_result result_type () const=0;
virtual Item_result cmp_type () const { return result_type(); }
virtual Item_result cast_to_int_type () const { return result_type(); }
static bool type_can_have_key_part(enum_field_types);
static enum_field_types field_type_merge(enum_field_types, enum_field_types);
static Item_result result_merge_type(enum_field_types);
bool eq(Field *field)

21
sql/sql_table.cc
View file

@ -3334,12 +3334,21 @@ bool mysql_alter_table(THD *thd,char *new_db, char *new_name,
continue; // Field is removed
uint key_part_length=key_part->length;
if (cfield->field) // Not new field
{ // Check if sub key
if (cfield->field->type() != FIELD_TYPE_BLOB &&
(cfield->field->pack_length() == key_part_length ||
cfield->length <= key_part_length /
key_part->field->charset()->mbmaxlen))
key_part_length=0; // Use whole field
{
/*
If the field can't have only a part used in a key according to its
new type, or should not be used partially according to its
previous type, or the field length is less than the key part
length, unset the key part length.
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->length && (cfield->length < key_part_length /
key_part->field->charset()->mbmaxlen)))
key_part_length= 0; // Use whole field
}
key_part_length /= key_part->field->charset()->mbmaxlen;
key_parts.push_back(new key_part_spec(cfield->field_name,