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).

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);
 }