MDEV-35035 Assertion failure in ha_blackhole::position upon INSERT into blackhole table with vector index

let's allow ::position() and ::rnd_pos() in blackhole.
::position() can be called directly after insert, it doesn't need
a search to happen, so it's possible.

::rnd_pos() can be called with a value that ::position() produced,
so, possible too.

Author: vuvova

mysql-test/main/blackhole.result

@@ -8,25 +8,38 @@ CREATE TABLE t2 (a INT UNSIGNED, b INT, UNIQUE KEY (a, b)) ENGINE=BLACKHOLE;
 SELECT 1 FROM t1 WHERE a = ANY (SELECT a FROM t2);
 1
 DROP TABLE t1, t2;
+#
+# Bug#19786309 -  CRASH IN UNLOCK TABLES AFTER LOCKING AND TRUNCATING TEMPORARY TABLE.
+#
 create temporary table t1 (a int) engine=blackhole;
 lock table t1 write;
 truncate table t1;
 select * from t1;
 a
 unlock tables;
 drop temporary table t1;
-End of 5.5 tests 
+# End of 5.5 tests
 #
 # Bug#13948247 DIVISION BY 0 IN GET_BEST_DISJUNCT_QUICK WITH FORCE INDEX GROUP BY
 #
 CREATE TABLE t1(a INT, b INT, c INT, KEY(c), UNIQUE(a)) ENGINE = BLACKHOLE;
 SELECT 0 FROM t1 FORCE INDEX FOR GROUP BY(a) WHERE a = 0 OR b = 0 AND c = 0;
 0
 DROP TABLE t1;
-End of 5.6 tests
+# End of 5.6 tests
+#
+# MDEV-24017 / bug 53588 test case.
+#
 CREATE TABLE `t` (
 `a` varchar(3000) NOT NULL default '',
 PRIMARY KEY  (`a`)
 ) ENGINE=BLACKHOLE CHARSET=latin1;
 DROP TABLE `t`;
-End of 10.1 tests
+# End of 10.1 tests
+#
+# MDEV-35035 Assertion failure in ha_blackhole::position upon INSERT into blackhole table with vector index
+#
+create table t (a int, v blob not null, vector index (v)) engine=blackhole;
+insert into t values (1,x'00000000');
+drop table t;
+# End of 11.7 tests

mysql-test/main/blackhole.test

@@ -17,17 +17,17 @@ SELECT 1 FROM t1 WHERE a = ANY (SELECT a FROM t2);
 
 DROP TABLE t1, t2;
 
-#
-# Bug#19786309 -  CRASH IN UNLOCK TABLES AFTER LOCKING AND TRUNCATING TEMPORARY TABLE.
-#
+--echo #
+--echo # Bug#19786309 -  CRASH IN UNLOCK TABLES AFTER LOCKING AND TRUNCATING TEMPORARY TABLE.
+--echo #
 create temporary table t1 (a int) engine=blackhole;
 lock table t1 write;
 truncate table t1;
 select * from t1;
 unlock tables;
 drop temporary table t1;
 
---echo End of 5.5 tests 
+--echo # End of 5.5 tests
 
 --echo #
 --echo # Bug#13948247 DIVISION BY 0 IN GET_BEST_DISJUNCT_QUICK WITH FORCE INDEX GROUP BY
@@ -37,11 +37,11 @@ CREATE TABLE t1(a INT, b INT, c INT, KEY(c), UNIQUE(a)) ENGINE = BLACKHOLE;
 SELECT 0 FROM t1 FORCE INDEX FOR GROUP BY(a) WHERE a = 0 OR b = 0 AND c = 0;
 DROP TABLE t1;
 
---echo End of 5.6 tests
+--echo # End of 5.6 tests
 
-#
-# MDEV-24017 / bug 53588 test case.
-#
+--echo #
+--echo # MDEV-24017 / bug 53588 test case.
+--echo #
 # Create long enough index (between 1000 and 3500). 1000 is the old value,
 # 3500 is innodb value (see ha_innobase::max_supported_key_length()). Without
 # the fix the test will fail with "Specified key was too long" error.
@@ -53,4 +53,13 @@ CREATE TABLE `t` (
 
 DROP TABLE `t`;
 
---echo End of 10.1 tests
+--echo # End of 10.1 tests
+
+--echo #
+--echo # MDEV-35035 Assertion failure in ha_blackhole::position upon INSERT into blackhole table with vector index
+--echo #
+create table t (a int, v blob not null, vector index (v)) engine=blackhole;
+insert into t values (1,x'00000000');
+drop table t;
+
+--echo # End of 11.7 tests

storage/blackhole/ha_blackhole.cc

@@ -148,15 +148,14 @@ int ha_blackhole::rnd_next(uchar *buf)
 int ha_blackhole::rnd_pos(uchar * buf, uchar *pos)
 {
   DBUG_ENTER("ha_blackhole::rnd_pos");
-  DBUG_ASSERT(0);
-  DBUG_RETURN(0);
+  DBUG_RETURN(HA_ERR_END_OF_FILE);
 }
 
 
 void ha_blackhole::position(const uchar *record)
 {
   DBUG_ENTER("ha_blackhole::position");
-  DBUG_ASSERT(0);
+  bzero(ref, ref_length);
   DBUG_VOID_RETURN;
 }