MDEV-27270: Wrong query plan with Range Checked for Each Record and O…

…RDER BY ... LIMIT

Followup to fix for MDEV-25858: When test_if_skip_sort_order() decides
to use an index to satisfy ORDER BY ... LIMIT clause, it should
disable "Range Checked for Each Record" optimization.

Do this in all cases.

mysql-test/r/order_by_innodb.result

@@ -198,5 +198,28 @@ id	id
 1	NULL
 2	1
 3	3
+#
+# MDEV-27270: Wrong query plan with Range Checked for Each Record and ORDER BY ... LIMIT
+#
+# This must NOT have "Range checked for each record" without any
+#   provisions to produce rows in the required ordering:
+explain
+select
+t1.id,t2.id
+from
+t1 left join
+t2 on t2.id2 = t1.id and
+t2.id = (select dd.id
+from t2 dd
+where
+dd.id2 = t1.id and
+d1 > '2019-02-06 00:00:00'
+                 order by
+dd.d1, dd.d2, dd.id limit 1
+);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	t1	index	NULL	PRIMARY	4	NULL	#	Using index
+1	PRIMARY	t2	eq_ref	PRIMARY,id2	PRIMARY	4	func	#	Using where
+2	DEPENDENT SUBQUERY	dd	range	id2,for_latest_sort	for_latest_sort	6	NULL	#	Using where
 drop table t1,t2;
 # End of 10.2 tests

mysql-test/t/order_by_innodb.test

@@ -184,6 +184,28 @@ from
                  order by
                    dd.d1 desc, dd.d2 desc, dd.id desc limit 1
                 );
+
+--echo #
+--echo # MDEV-27270: Wrong query plan with Range Checked for Each Record and ORDER BY ... LIMIT
+--echo #
+
+--echo # This must NOT have "Range checked for each record" without any
+--echo #   provisions to produce rows in the required ordering:
+--replace_column 9 #
+explain
+select
+  t1.id,t2.id
+from
+  t1 left join
+  t2 on t2.id2 = t1.id and
+        t2.id = (select dd.id
+                 from t2 dd
+                 where
+                    dd.id2 = t1.id and
+                    d1 > '2019-02-06 00:00:00'
+                 order by
+                   dd.d1, dd.d2, dd.id limit 1
+                );
 drop table t1,t2;
 
 --echo # End of 10.2 tests

sql/sql_select.cc

@@ -21986,7 +21986,15 @@ test_if_skip_sort_order(JOIN_TAB *tab,ORDER *order,ha_rows select_limit,
       }
     }
     else if (select && select->quick)
+    {
+      /* Cancel "Range checked for each record" */
+      if (tab->use_quick == 2)
+      {
+        tab->use_quick= 1;
+        tab->read_first_record= join_init_read_record;
+      }
       select->quick->need_sorted_output();
+    }
 
     tab->read_record.unlock_row= (tab->type == JT_EQ_REF) ?
                                  join_read_key_unlock_row : rr_unlock_row;