Bug #37894: Assertion in init_read_record_seq in handler.h line 1444

Select with a "NULL NOT IN" condition containing complex
subselect from the same table as in the outer select failed
with an assertion.


The failure was caused by a concatenation of circumstances:
1) an inner select was optimized by make_join_statistics to use
   the QUICK_RANGE_SELECT access method (that implies an index
   scan of the table);
2) a subselect was independent (constant) from the outer select;
3) a condition was pushed down into inner select.

During the evaluation of a constant IN expression an optimizer
temporary changed the access method from index scan to table
scan, but an engine handler was already initialized for index
access by make_join_statistics. That caused an assertion.


Unnecessary index initialization has been removed from
the QUICK_RANGE_SELECT::init method (QUICK_RANGE_SELECT::reset
reinvokes this initialization).

mysql-test/r/subselect3.result

@@ -779,4 +779,20 @@ SELECT 1 FROM t1 WHERE t1.a NOT IN (SELECT 1 FROM t1, t2 WHERE 0);
 1
 1
 DROP TABLE t1, t2;
+CREATE TABLE t1 (
+pk INT PRIMARY KEY,
+int_key INT,
+varchar_key VARCHAR(5) UNIQUE,
+varchar_nokey VARCHAR(5)
+);
+INSERT INTO t1 VALUES (9, 7,NULL,NULL), (10,8,'p' ,'p');
+SELECT varchar_nokey
+FROM t1
+WHERE NULL NOT IN (
+SELECT INNR.pk FROM t1 AS INNR2
+LEFT JOIN t1 AS INNR ON ( INNR2.int_key = INNR.int_key )
+WHERE INNR.varchar_key > 'n{'
+);
+varchar_nokey
+DROP TABLE t1;
 End of 5.0 tests

mysql-test/t/subselect3.test

@@ -618,4 +618,26 @@ SELECT 1 FROM t1 WHERE t1.a NOT IN (SELECT 1 FROM t1, t2 WHERE 0);
 
 DROP TABLE t1, t2;
 
+#
+# Bug #37894: Assertion in init_read_record_seq in handler.h line 1444
+#
+
+CREATE TABLE t1 (
+  pk INT PRIMARY KEY,
+  int_key INT,
+  varchar_key VARCHAR(5) UNIQUE,
+  varchar_nokey VARCHAR(5)
+);
+INSERT INTO t1 VALUES (9, 7,NULL,NULL), (10,8,'p' ,'p');
+
+SELECT varchar_nokey
+FROM t1
+WHERE NULL NOT IN (
+ SELECT INNR.pk FROM t1 AS INNR2
+   LEFT JOIN t1 AS INNR ON ( INNR2.int_key = INNR.int_key )
+   WHERE INNR.varchar_key > 'n{'
+);
+
+DROP TABLE t1;
+
 --echo End of 5.0 tests

sql/opt_range.cc

@@ -1015,7 +1015,7 @@ int QUICK_RANGE_SELECT::init()
 
   if (file->inited != handler::NONE)
     file->ha_index_or_rnd_end();
-  DBUG_RETURN(error= file->ha_index_init(index));
+  DBUG_RETURN(FALSE);
 }