Fixed LP bug #672551.

Made sure that the function that copy a long varchar field from the record
buffer into a key buffer does not copy bytes after the field value.

mysql-test/r/join_cache.result

@@ -5675,4 +5675,44 @@ f	5
 f	5
 SET SESSION join_cache_level = DEFAULT;
 DROP TABLE t1,t2;
+#
+# Bug #672551: hash join over a long varchar field
+#
+CREATE TABLE t1 (
+pk int PRIMARY KEY,
+a varchar(512) CHARSET latin1 COLLATE latin1_bin DEFAULT NULL,
+INDEX idx (a)
+);
+INSERT INTO t1 VALUES (2, 'aa'), (5, 'ccccccc'), (3, 'bb');
+CREATE TABLE t2(
+pk int PRIMARY KEY,
+a varchar(512) CHARSET latin1 COLLATE latin1_bin DEFAULT NULL,
+INDEX idx (a)
+);
+INSERT INTO t2 VALUES 
+(10, 'a'), (20, 'c'), (30, 'aa'), (4, 'bb'),
+(11, 'a'), (21, 'c'), (31, 'aa'), (41, 'cc'),
+(12, 'a'), (22, 'c'), (32, 'bb'), (42, 'aa');
+SELECT * FROM t1,t2 WHERE t2.a=t1.a;
+pk	a	pk	a
+2	aa	30	aa
+2	aa	31	aa
+2	aa	42	aa
+3	bb	4	bb
+3	bb	32	bb
+SET SESSION join_cache_level = 4;
+EXPLAIN
+SELECT * FROM t1,t2 WHERE t2.a=t1.a;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	ALL	idx	NULL	NULL	NULL	3	Using where
+1	SIMPLE	t2	ref	idx	idx	515	test.t1.a	2	Using join buffer (flat, BNLH join)
+SELECT * FROM t1,t2 WHERE t2.a=t1.a;
+pk	a	pk	a
+2	aa	30	aa
+3	bb	4	bb
+2	aa	31	aa
+3	bb	32	bb
+2	aa	42	aa
+SET SESSION join_cache_level = DEFAULT;
+DROP TABLE t1,t2;
 set @@optimizer_switch=@save_optimizer_switch;

mysql-test/t/join_cache.test

@@ -2358,5 +2358,37 @@ SET SESSION join_cache_level = DEFAULT;
 
 DROP TABLE t1,t2;
 
+--echo #
+--echo # Bug #672551: hash join over a long varchar field
+--echo #
+
+CREATE TABLE t1 (
+  pk int PRIMARY KEY,
+  a varchar(512) CHARSET latin1 COLLATE latin1_bin DEFAULT NULL,
+  INDEX idx (a)
+);
+INSERT INTO t1 VALUES (2, 'aa'), (5, 'ccccccc'), (3, 'bb');
+
+CREATE TABLE t2(
+  pk int PRIMARY KEY,
+  a varchar(512) CHARSET latin1 COLLATE latin1_bin DEFAULT NULL,
+  INDEX idx (a)
+);
+INSERT INTO t2 VALUES 
+  (10, 'a'), (20, 'c'), (30, 'aa'), (4, 'bb'),
+  (11, 'a'), (21, 'c'), (31, 'aa'), (41, 'cc'),
+  (12, 'a'), (22, 'c'), (32, 'bb'), (42, 'aa');
+
+SELECT * FROM t1,t2 WHERE t2.a=t1.a;
+
+SET SESSION join_cache_level = 4;
+EXPLAIN
+SELECT * FROM t1,t2 WHERE t2.a=t1.a;
+SELECT * FROM t1,t2 WHERE t2.a=t1.a;
+
+SET SESSION join_cache_level = DEFAULT;
+
+DROP TABLE t1,t2;
+
 # this must be the last command in the file
 set @@optimizer_switch=@save_optimizer_switch;

sql/field_conv.cc

@@ -449,7 +449,8 @@ static void do_varstring1(Copy_field *copy)
   if (length > copy->to_length- 1)
   {
     length=copy->to_length - 1;
-    if (copy->from_field->table->in_use->count_cuted_fields)
+    if (copy->from_field->table->in_use->count_cuted_fields &&
+        copy->to_field)
       copy->to_field->set_warning(MYSQL_ERROR::WARN_LEVEL_WARN,
                                   WARN_DATA_TRUNCATED, 1);
   }
@@ -485,7 +486,8 @@ static void do_varstring2(Copy_field *copy)
   if (length > copy->to_length- HA_KEY_BLOB_LENGTH)
   {
     length=copy->to_length-HA_KEY_BLOB_LENGTH;
-    if (copy->from_field->table->in_use->count_cuted_fields)
+    if (copy->from_field->table->in_use->count_cuted_fields &&
+        copy->to_field)
       copy->to_field->set_warning(MYSQL_ERROR::WARN_LEVEL_WARN,
                                   WARN_DATA_TRUNCATED, 1);
   }
@@ -549,9 +551,16 @@ void Copy_field::set(uchar *to,Field *from)
       do_copy=	  do_field_to_null_str;
   }
   else
-  {
+  { 
     to_null_ptr=  0;				// For easy debugging
-    do_copy=	  do_field_eq;
+    /* Setup optimal copying for varchar */
+    if (from->real_type() == MYSQL_TYPE_VARCHAR)
+    {
+      do_copy= (((Field_varstring*) from)->length_bytes == 1 ?
+                 do_varstring1 : do_varstring2);
+    }  
+    else
+      do_copy= do_field_eq;
   }
 }
 
@@ -710,6 +719,10 @@ Copy_field::get_copy_func(Field *to,Field *from)
                                                     do_varstring1_mb) :
                   (from->charset()->mbmaxlen == 1 ? do_varstring2 :
                                                     do_varstring2_mb));
+        else 
+          return  (((Field_varstring*) from)->length_bytes == 1 ?
+                    do_varstring1 : do_varstring2);
+
       }
       else if (to_length < from_length)
 	return (from->charset()->mbmaxlen == 1 ?