bk commit into 5.0 tree (jimw:1.1913) BUG#10543

[Jim Winstead]

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5.0 repository of jimw. When jimw does a push these changes will
be propagated to the main repository and, within 24 hours after the
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ChangeSet
  1.1913 05/06/02 10:00:36 jimw@stripped +3 -0
  Additional tweak to fix for bug #10543, to prevent a change in
  behavior when extending fields that were fully part of a
  multi-part key.

  sql/sql_table.cc
    1.247 05/06/02 10:00:32 jimw@stripped +4 -0
    Reset key_part_length when old field length was the same as the
    old key_part_length.

  mysql-test/t/key.test
    1.20 05/06/02 10:00:32 jimw@stripped +13 -0
    Add test for behavior of extending fields in a multi-part key
    that were defined with a partial length the same as their
    field length.

  mysql-test/r/key.result
    1.25 05/06/02 10:00:32 jimw@stripped +25 -0
    Update results

# This is a BitKeeper patch.  What follows are the unified diffs for the
# set of deltas contained in the patch.  The rest of the patch, the part
# that BitKeeper cares about, is below these diffs.
# User:	jimw
# Host:	rama.(none)
# Root:	/home/jimw/my/mysql-5.0-10543

--- 1.246/sql/sql_table.cc	2005-05-25 18:11:44 -07:00
+++ 1.247/sql/sql_table.cc	2005-06-02 10:00:32 -07:00
@@ -3341,11 +3341,15 @@
           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

--- 1.24/mysql-test/r/key.result	2004-11-22 11:54:41 -08:00
+++ 1.25/mysql-test/r/key.result	2005-06-02 10:00:32 -07:00
@@ -329,3 +329,28 @@
 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;

--- 1.19/mysql-test/t/key.test	2004-11-22 11:54:42 -08:00
+++ 1.20/mysql-test/t/key.test	2005-06-02 10:00:32 -07:00
@@ -324,3 +324,16 @@
 --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;