BUG#933407: Valgrind warnings in mark_as_null_row with...

BUG#933407: Valgrind warnings in mark_as_null_row with materialization+semijoin, STRAIGHT_JOIN, impossible WHERE
- In return_zero_rows(), don't call mark_as_null_row() for semi-join 
  materialized tables, because 1) they may have been already freed, and 
  2)there is no real need to call mark_as_null_row() for them.
  

mysql-test/r/subselect_mat.result

@@ -1848,6 +1848,19 @@ a	b
 7	5
 3	3
 drop table t1,t2;
+#
+# BUG#933407: Valgrind warnings in mark_as_null_row with materialization+semijoin, STRAIGHT_JOIN, impossible WHERE
+#
+CREATE TABLE t1 (a INT);
+INSERT INTO t1 VALUES (0),(8);
+SELECT STRAIGHT_JOIN MIN(a) FROM t1
+WHERE a IN (
+SELECT a FROM t1
+WHERE 'condition'='impossible'
+  );
+MIN(a)
+NULL
+DROP TABLE t1;
 # This must be at the end:
 set optimizer_switch=@subselect_sj_mat_tmp;
 set join_cache_level=@save_join_cache_level;

mysql-test/r/subselect_sj_mat.result

@@ -1885,6 +1885,19 @@ a	b
 7	5
 3	3
 drop table t1,t2;
+#
+# BUG#933407: Valgrind warnings in mark_as_null_row with materialization+semijoin, STRAIGHT_JOIN, impossible WHERE
+#
+CREATE TABLE t1 (a INT);
+INSERT INTO t1 VALUES (0),(8);
+SELECT STRAIGHT_JOIN MIN(a) FROM t1
+WHERE a IN (
+SELECT a FROM t1
+WHERE 'condition'='impossible'
+  );
+MIN(a)
+NULL
+DROP TABLE t1;
 # This must be at the end:
 set optimizer_switch=@subselect_sj_mat_tmp;
 set join_cache_level=@save_join_cache_level;

mysql-test/t/subselect_sj_mat.test

@@ -1545,6 +1545,19 @@ select * from t1 where t1.a in (select a from t2 where t2.a=7 or t2.b<=1);
 
 drop table t1,t2;
 
+--echo #
+--echo # BUG#933407: Valgrind warnings in mark_as_null_row with materialization+semijoin, STRAIGHT_JOIN, impossible WHERE
+--echo #
+CREATE TABLE t1 (a INT);
+INSERT INTO t1 VALUES (0),(8);
+
+SELECT STRAIGHT_JOIN MIN(a) FROM t1
+WHERE a IN (
+    SELECT a FROM t1
+    WHERE 'condition'='impossible'
+  );
+
+DROP TABLE t1;
 
 --echo # This must be at the end:
 set optimizer_switch=@subselect_sj_mat_tmp;

sql/sql_select.cc

@@ -10431,10 +10431,22 @@ return_zero_rows(JOIN *join, select_result *result, List<TABLE_LIST> &tables,
 
   if (send_row)
   {
+    /*
+      Set all tables to have NULL row. This is needed as we will be evaluating
+      HAVING condition.
+    */
     List_iterator<TABLE_LIST> ti(tables);
     TABLE_LIST *table;
     while ((table= ti++))
-      mark_as_null_row(table->table);		// All fields are NULL
+    {
+      /*
+        Don't touch semi-join materialization tables, as the above join_free()
+        call has freed them (and HAVING clause can't have references to them 
+        anyway).
+      */
+      if (!table->is_jtbm())
+        mark_as_null_row(table->table);		// All fields are NULL
+    }
     if (having &&
         !having->walk(&Item::clear_sum_processor, FALSE, NULL) &&
         having->val_int() == 0)