BUG#12873 - BTREE index on MEMORY table with multiple NULL values

            doesn't work properly

Unique BTREE index on MEMORY table refuse multiple NULL values.

Fixed search_flag to allow multiple null values inside unique key.

heap/hp_write.c

@@ -105,7 +105,7 @@ int hp_rb_write_key(HP_INFO *info, HP_KEYDEF *keyinfo, const byte *record,
   custom_arg.key_length= hp_rb_make_key(keyinfo, info->recbuf, record, recpos);
   if (keyinfo->flag & HA_NOSAME)
   {
-    custom_arg.search_flag= SEARCH_FIND | SEARCH_SAME | SEARCH_UPDATE;
+    custom_arg.search_flag= SEARCH_FIND | SEARCH_UPDATE;
     keyinfo->rb_tree.flag= TREE_NO_DUPS;
   }
   else

mysql-test/r/heap_btree.result

@@ -256,3 +256,6 @@ SELECT INDEX_LENGTH FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA=DATABASE()
 INDEX_LENGTH
 21
 DROP TABLE t1;
+CREATE TABLE t1 (a INT, UNIQUE USING BTREE(a)) ENGINE=MEMORY;
+INSERT INTO t1 VALUES(NULL),(NULL);
+DROP TABLE t1;

mysql-test/t/heap_btree.test

@@ -176,4 +176,12 @@ UPDATE t1 SET val=1;
 SELECT INDEX_LENGTH FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA=DATABASE() AND TABLE_NAME='t1';
 DROP TABLE t1;
 
+#
+# BUG#12873 - BTREE index on MEMORY table with multiple NULL values doesn't
+# work properly
+#
+CREATE TABLE t1 (a INT, UNIQUE USING BTREE(a)) ENGINE=MEMORY;
+INSERT INTO t1 VALUES(NULL),(NULL);
+DROP TABLE t1;
+
 # End of 4.1 tests