Fixed BUG#51763 Can't delete rows from MEMORY table with HASH key

mysql-test/suite/heap/heap.result:
  Added test case
mysql-test/suite/heap/heap.test:
  Added test case
storage/heap/hp_delete.c:
  Fixed that we don't change order of keys for the current key when we delete them from the hash table.
  Fixed that 'current_hash_ptr' is correct after heap_delete_key().
  Don't "reset current_hash_ptr" on delete; This will improve time a lot for delete of rows when not all rows matches the search criteria.

1 files changed, 24 insertions, 0 deletions

diff --git a/mysql-test/suite/heap/heap.test b/mysql-test/suite/heap/heap.test
index 6f5046af139..a421304d6d8 100644
--- a/mysql-test/suite/heap/heap.test
+++ b/mysql-test/suite/heap/heap.test
@@ -537,3 +537,27 @@ insert into t1 select rand(100000000) from t1;
 --replace_result 40512 81024 60512 121024
 select data_length,index_length from information_schema.tables where table_schema="test" and table_name="t1";
 drop table t1;
+
+#
+# BUG#51763 Can't delete rows from MEMORY table with HASH key
+#
+
+CREATE TABLE t1 (
+  id int(11) NOT NULL AUTO_INCREMENT,
+  color enum('GREEN', 'WHITE')  DEFAULT NULL,
+  ts int,
+  PRIMARY KEY (id),
+  KEY color (color) USING HASH
+) ENGINE=MEMORY DEFAULT CHARSET=utf8;
+
+INSERT INTO t1 VALUES("1","GREEN",1);
+INSERT INTO t1 VALUES("2","GREEN",1);
+INSERT INTO t1 VALUES("3","GREEN",1);
+INSERT INTO t1 VALUES("4","GREEN",1);
+INSERT INTO t1 VALUES("5","GREEN",1);
+INSERT INTO t1 VALUES("6","GREEN",1);
+DELETE FROM t1 WHERE id = 1;
+INSERT INTO t1 VALUES("7","GREEN", 2);
+DELETE FROM t1 WHERE ts = 1 AND color = 'GREEN';
+SELECT * from t1 WHERE ts = 1 AND color = 'GREEN';
+DROP TABLE t1;