Bug#19717: The blackhole engine is returning an OK flag in

index_read(), whereas it must return HA_ERR_END_OF_FILE
instead (as there are by definition no rows in a table of 
that engine.

mysql-test/r/blackhole.result

@@ -123,3 +123,14 @@ master-bin.000001	#	Query	1	#	use `test`; create table t3 like t1
 master-bin.000001	#	Query	1	#	use `test`; insert into t1 select * from t3
 master-bin.000001	#	Query	1	#	use `test`; replace into t1 select * from t3
 drop table t1,t2,t3;
+CREATE TABLE t1(a INT, b INT) ENGINE=BLACKHOLE;
+DELETE FROM t1 WHERE a=10;
+ALTER TABLE t1 ADD INDEX(a);
+DELETE FROM t1 WHERE a=10;
+ALTER TABLE t1 DROP INDEX a;
+ALTER TABLE t1 ADD UNIQUE INDEX(a);
+DELETE FROM t1 WHERE a=10;
+ALTER TABLE t1 DROP INDEX a;
+ALTER TABLE t1 ADD PRIMARY KEY(a);
+DELETE FROM t1 WHERE a=10;
+DROP TABLE t1;

mysql-test/t/blackhole.test

@@ -127,4 +127,19 @@ show binlog events;
 
 drop table t1,t2,t3;
 
+#
+#Bug#19717: DELETE Query Error on BLACKHOLE when using WHERE on column with UNIQUE INDEX
+#
+CREATE TABLE t1(a INT, b INT) ENGINE=BLACKHOLE;
+DELETE FROM t1 WHERE a=10;
+ALTER TABLE t1 ADD INDEX(a);
+DELETE FROM t1 WHERE a=10;
+ALTER TABLE t1 DROP INDEX a;
+ALTER TABLE t1 ADD UNIQUE INDEX(a);
+DELETE FROM t1 WHERE a=10;
+ALTER TABLE t1 DROP INDEX a;
+ALTER TABLE t1 ADD PRIMARY KEY(a);
+DELETE FROM t1 WHERE a=10;
+DROP TABLE t1;
+
 # End of 4.1 tests

sql/ha_blackhole.cc

@@ -180,7 +180,7 @@ int ha_blackhole::index_read(byte * buf, const byte * key,
                              uint key_len, enum ha_rkey_function find_flag)
 {
   DBUG_ENTER("ha_blackhole::index_read");
-  DBUG_RETURN(0);
+  DBUG_RETURN(HA_ERR_END_OF_FILE);
 }