From c3c483e0918aaba7925a86a53018fd4cb5e03a82 Mon Sep 17 00:00:00 2001
From: unknown <bar@mysql.com>
Date: Mon, 23 Aug 2004 20:12:39 +0500
Subject: [PATCH] Bug#4594: column index make = failed for gbk, but like works
 Fix for HEAP+HASH prefix keys.

---
 mysql-test/r/ctype_utf8.result | 10 ++++++++++
 mysql-test/t/ctype_utf8.test   | 12 ++++++++++++
 sql/key.cc                     | 15 +++++++++++----
 3 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/mysql-test/r/ctype_utf8.result b/mysql-test/r/ctype_utf8.result
index 6a0bd21c551..ef5ec012078 100644
--- a/mysql-test/r/ctype_utf8.result
+++ b/mysql-test/r/ctype_utf8.result
@@ -560,3 +560,13 @@ select * from t1 where str='str';
 str
 str
 drop table t1;
+create table t1 (
+str varchar(255) character set utf8 not null,
+key str using hash (str(2))
+) engine=heap;
+INSERT INTO t1 VALUES ('str');
+INSERT INTO t1 VALUES ('str2');
+select * from t1 where str='str';
+str
+str
+drop table t1;
diff --git a/mysql-test/t/ctype_utf8.test b/mysql-test/t/ctype_utf8.test
index 17b89ba1050..83055d05830 100644
--- a/mysql-test/t/ctype_utf8.test
+++ b/mysql-test/t/ctype_utf8.test
@@ -417,3 +417,15 @@ INSERT INTO t1 VALUES ('str');
 INSERT INTO t1 VALUES ('str2');
 select * from t1 where str='str';
 drop table t1;
+
+# the same for HEAP+HASH
+#
+
+create table t1 (
+  str varchar(255) character set utf8 not null,
+  key str using hash (str(2))
+) engine=heap;
+INSERT INTO t1 VALUES ('str');
+INSERT INTO t1 VALUES ('str2');
+select * from t1 where str='str';
+drop table t1;
diff --git a/sql/key.cc b/sql/key.cc
index 9425a368669..b1f4c9533a9 100644
--- a/sql/key.cc
+++ b/sql/key.cc
@@ -211,10 +211,17 @@ bool key_cmp_if_same(TABLE *table,const byte *key,uint idx,uint key_length)
       if (!(key_part->key_type & (FIELDFLAG_NUMBER+FIELDFLAG_BINARY+
 				  FIELDFLAG_PACK)))
       {
-	if (my_strnncoll(key_part->field->charset(),
-			 (const uchar*) key, length,
-		         (const uchar*) table->record[0]+key_part->offset,
-			 length))
+        CHARSET_INFO *cs= key_part->field->charset();
+        uint char_length= key_part->length / cs->mbmaxlen;
+        const byte *pos= table->record[0] + key_part->offset;
+        if (length > char_length)
+        {
+          char_length= my_charpos(cs, pos, pos + length, char_length);
+          set_if_smaller(char_length, length);
+        }
+	if (cs->coll->strnncollsp(cs,
+                                  (const uchar*) key, length,
+                                  (const uchar*) pos, char_length))
 	  return 1;
       }
       else if (memcmp(key,table->record[0]+key_part->offset,length))