Bug #31974: Wrong EXPLAIN output

The fix for bug 31148 is not correct. It does not
have a relation to the problem described in this bug.
And removing the fix will not make the bug to re-appear.
Fixed the bug #31974 by removing the fix for bug 31148
and adding a test case.


mysql-test/r/key.result:
  Bug #31974: test case
mysql-test/t/key.test:
  Bug #31974: test case
sql/sql_select.cc:
  Bug #31974: revert the fix for bug 31148

mysql-test/r/key.result

@@ -545,3 +545,17 @@ c1
 1
 1
 DROP TABLE t1;
+CREATE TABLE t1 (a INT, b INT, INDEX (a,b));
+INSERT INTO t1 (a, b)
+VALUES
+(1,1), (1,2), (1,3), (1,4), (1,5),
+(2,2), (2,3), (2,1), (3,1), (4,1), (4,2), (4,3), (4,4), (4,5), (4,6);
+EXPLAIN SELECT 1 FROM t1 AS t1_outer WHERE 
+(SELECT max(b) FROM t1 GROUP BY a HAVING a < 2) > 12;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE
+2	SUBQUERY	t1	range	NULL	a	5	NULL	8	Using index for group-by
+SELECT 1 as RES FROM t1 AS t1_outer WHERE 
+(SELECT max(b) FROM t1 GROUP BY a HAVING a < 2) > 12;
+RES
+DROP TABLE t1;

mysql-test/t/key.test

@@ -524,3 +524,20 @@ ORDER BY (
   LIMIT 1);
 
 DROP TABLE t1;
+
+
+#
+# Bug #31974: Wrong EXPLAIN output
+#
+
+CREATE TABLE t1 (a INT, b INT, INDEX (a,b));
+INSERT INTO t1 (a, b)
+   VALUES
+     (1,1), (1,2), (1,3), (1,4), (1,5),
+     (2,2), (2,3), (2,1), (3,1), (4,1), (4,2), (4,3), (4,4), (4,5), (4,6);
+EXPLAIN SELECT 1 FROM t1 AS t1_outer WHERE 
+  (SELECT max(b) FROM t1 GROUP BY a HAVING a < 2) > 12;
+SELECT 1 as RES FROM t1 AS t1_outer WHERE 
+  (SELECT max(b) FROM t1 GROUP BY a HAVING a < 2) > 12;
+
+DROP TABLE t1;

sql/sql_select.cc

@@ -6651,17 +6651,10 @@ void JOIN::cleanup(bool full)
       for (tab= join_tab, end= tab+tables; tab != end; tab++)
       {
 	if (tab->table)
-        {
-          if (tab->table->key_read)
-          {
-            tab->table->key_read= 0;
-            tab->table->file->extra(HA_EXTRA_NO_KEYREAD);
-          }
           tab->table->file->ha_index_or_rnd_end();
       }
     }
   }
-  }
   /*
     We are not using tables anymore
     Unlock all tables. We may be in an INSERT .... SELECT statement.