BUG#58456 - Assertion 0 in QUICK_INDEX_MERGE_SELECT::need_sorted_output

in opt_range.h

In this bug, there are two alternative access plans: 
 * Index merge range access
 * Const ref access

best_access_path() decided that the ref access was preferrable, 
but make_join_select() still decided to point 
SQL_SELECT::quick to the index merge because the table had 
type==JT_CONST which was not handled. 

At the same time the table's ref.key still referred to the 
index the ref access would use indicating that ref access 
should be used. In this state, different parts of the 
optimizer code have different perceptions of which access path
is in use (ref or range).

test_if_skip_sort_order() was called to check if the ref access
needed ordering, but test_if_skip_sort_order() got confused and
requested the index merge to return records in sorted order. 
Index merge cannot do this, and fired an ASSERT.

The fix is to take join_tab->type==JT_CONST into concideration
when make_join_select() decides whether or not to use the 
range access method.

mysql-test/r/join_outer_innodb.result

@@ -17,3 +17,38 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t2	index	NULL	fkey	5	NULL	5	Using index
 1	SIMPLE	t1	eq_ref	PRIMARY	PRIMARY	4	test.t2.fkey	1	Using where
 DROP TABLE t1,t2;
+#
+# BUG#58456: Assertion 0 in QUICK_INDEX_MERGE_SELECT::need_sorted_output
+#            in opt_range.h
+#
+CREATE TABLE t1 (
+col_int INT,
+col_int_key INT,
+pk INT NOT NULL,
+PRIMARY KEY (pk),
+KEY col_int_key (col_int_key)
+) ENGINE=InnoDB;
+INSERT INTO t1 VALUES (NULL,1,1), (6,2,2), (5,3,3), (NULL,4,4);
+INSERT INTO t1 VALUES (1,NULL,6), (8,5,7), (NULL,8,8), (8,NULL,5);
+CREATE TABLE t2 (
+pk INT PRIMARY KEY
+) ENGINE=InnoDB;
+
+EXPLAIN SELECT t1.pk
+FROM t2 LEFT JOIN t1 ON t2.pk = t1.col_int
+WHERE t1.col_int_key BETWEEN 5 AND 6 
+AND t1.pk IS NULL OR t1.pk IN (5)
+ORDER BY pk;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	const	PRIMARY,col_int_key	PRIMARY	4	const	2	Using where
+1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.col_int	1	Using index
+
+SELECT t1.pk
+FROM t2 LEFT JOIN t1 ON t2.pk = t1.col_int
+WHERE t1.col_int_key BETWEEN 5 AND 6 
+AND t1.pk IS NULL OR t1.pk IN (5)
+ORDER BY pk;
+pk
+
+DROP TABLE t1,t2;
+# End BUG#58456

mysql-test/t/join_outer_innodb.test

@@ -24,3 +24,40 @@ SELECT COUNT(*) FROM t2 LEFT JOIN t1 ON t2.fkey = t1.id
   WHERE t1.name LIKE 'A%' OR FALSE;
 
 DROP TABLE t1,t2;
+
+--echo #
+--echo # BUG#58456: Assertion 0 in QUICK_INDEX_MERGE_SELECT::need_sorted_output
+--echo #            in opt_range.h
+--echo #
+
+CREATE TABLE t1 (
+  col_int INT,
+  col_int_key INT,
+  pk INT NOT NULL,
+  PRIMARY KEY (pk),
+  KEY col_int_key (col_int_key)
+) ENGINE=InnoDB;
+
+INSERT INTO t1 VALUES (NULL,1,1), (6,2,2), (5,3,3), (NULL,4,4);
+INSERT INTO t1 VALUES (1,NULL,6), (8,5,7), (NULL,8,8), (8,NULL,5);
+
+CREATE TABLE t2 (
+  pk INT PRIMARY KEY
+) ENGINE=InnoDB;
+
+let $query=
+SELECT t1.pk
+FROM t2 LEFT JOIN t1 ON t2.pk = t1.col_int
+WHERE t1.col_int_key BETWEEN 5 AND 6 
+      AND t1.pk IS NULL OR t1.pk IN (5)
+ORDER BY pk;
+
+--echo
+--eval EXPLAIN $query
+--echo
+--eval $query
+--echo
+
+DROP TABLE t1,t2;
+
+--echo # End BUG#58456

sql/sql_select.cc

@@ -6499,10 +6499,12 @@ make_join_select(JOIN *join,SQL_SELECT *select,COND *cond)
 	{
 	  /* Use quick key read if it's a constant and it's not used
 	     with key reading */
-	  if (tab->needed_reg.is_clear_all() && tab->type != JT_EQ_REF
+          if (tab->needed_reg.is_clear_all() && tab->type != JT_EQ_REF &&
-	      && tab->type != JT_FT && (tab->type != JT_REF ||
+              tab->type != JT_FT &&
-               (uint) tab->ref.key == tab->quick->index))
+              ((tab->type != JT_CONST && tab->type != JT_REF) ||
-	  {
+               (uint)tab->ref.key == tab->quick->index))
+          {
+            DBUG_ASSERT(tab->quick->index != MAX_KEY);
 	    sel->quick=tab->quick;		// Use value from get_quick_...
 	    sel->quick_keys.clear_all();
 	    sel->needed_reg.clear_all();
@@ -13857,7 +13859,7 @@ check_reverse_order:
   SYNOPSIS
    create_sort_index()
      thd		Thread handler
-     tab		Table to sort (in join structure)
+     join		Join with table to sort
      order		How table should be sorted
      filesort_limit	Max number of rows that needs to be sorted
      select_limit	Max number of rows in final output
@@ -13867,8 +13869,8 @@ check_reverse_order:
 
 
   IMPLEMENTATION
-   - If there is an index that can be used, 'tab' is modified to use
+   - If there is an index that can be used, the first non-const join_tab in
-     this index.
+     'join' is modified to use this index.
    - If no index, create with filesort() an index file that can be used to
      retrieve rows in order (should be done with 'read_record').
      The sorted data is stored in tab->table and will be freed when calling