Commit f0329bfb authored by unknown's avatar unknown
Browse files

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


mysql-test/r/type_varchar.result:
  Update results
mysql-test/t/type_varchar.test:
  Add new regression test
sql/field.cc:
  Add Field::type_can_have_key_part() static method
sql/field.h:
  Add Field::type_can_have_key_part() signature.
sql/sql_table.cc:
  Only reset the length of a key part when changing from a
  field type that can't be used partially to a field that can,
  or vice versa, or when the part is smaller than the length
  of the field.
parent f0f9b595

mysql-test/r/type_varchar.result

+23 −0
Original line number Diff line number Diff line
@@ -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;

mysql-test/t/type_varchar.test

+12 −0
Original line number Diff line number Diff line
@@ -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;

sql/field.cc

+33 −0
Original line number Diff line number Diff line
@@ -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

*/

sql/field.h

+1 −0
Original line number Diff line number Diff line
@@ -119,6 +119,7 @@ class Field 
  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)

sql/sql_table.cc

+15 −6
Original line number Diff line number Diff line
@@ -3334,11 +3334,20 @@ 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))

      {

        /*

          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;