BUG#906385: EXPLAIN EXTENDED crashes in TABLE_LIST::print with limited max_join_size

- Take into account that subquery's optimization can fail because of @@max_join_size error.

mysql-test/r/subselect_sj2_mat.result

@@ -897,3 +897,25 @@ set optimizer_switch=default;
 select @@optimizer_switch like '%materialization=on%';
 @@optimizer_switch like '%materialization=on%'
 1
+#
+# BUG#906385: EXPLAIN EXTENDED crashes in TABLE_LIST::print with limited max_join_size
+#
+CREATE TABLE t1 ( a INT );
+CREATE TABLE t2 ( b INT );
+INSERT INTO t1 VALUES (1),(2);
+INSERT INTO t2 VALUES
+(1),(2),(3),(4),(5),
+(6),(7),(8),(9),(10),
+(11),(12),(13),(14),(15),
+(16),(17),(18),(19),(20);
+set @tmp_906385=@@max_join_size;
+SET max_join_size = 80;
+EXPLAIN EXTENDED
+SELECT COUNT(*) FROM t1
+WHERE a IN
+( SELECT b FROM t2 GROUP BY b )
+AND ( 6 ) IN
+( SELECT MIN( t2.b ) FROM t2 alias1, t2 );
+ERROR 42000: The SELECT would examine more than MAX_JOIN_SIZE rows; check your WHERE and use SET SQL_BIG_SELECTS=1 or SET MAX_JOIN_SIZE=# if the SELECT is okay
+DROP TABLE t1, t2;
+set max_join_size= @tmp_906385;

mysql-test/t/subselect_sj2_mat.test

@@ -8,3 +8,32 @@ set optimizer_switch='mrr=on,mrr_sort_keys=on,index_condition_pushdown=on';
 
 set optimizer_switch=default;
 select @@optimizer_switch like '%materialization=on%';
+
+--echo #
+--echo # BUG#906385: EXPLAIN EXTENDED crashes in TABLE_LIST::print with limited max_join_size
+--echo #
+CREATE TABLE t1 ( a INT );
+CREATE TABLE t2 ( b INT );
+
+INSERT INTO t1 VALUES (1),(2);
+INSERT INTO t2 VALUES
+  (1),(2),(3),(4),(5),
+  (6),(7),(8),(9),(10),
+  (11),(12),(13),(14),(15),
+  (16),(17),(18),(19),(20);
+
+set @tmp_906385=@@max_join_size;
+SET max_join_size = 80;
+
+--error ER_TOO_BIG_SELECT
+EXPLAIN EXTENDED
+SELECT COUNT(*) FROM t1
+WHERE a IN
+      ( SELECT b FROM t2 GROUP BY b )
+  AND ( 6 ) IN
+  ( SELECT MIN( t2.b ) FROM t2 alias1, t2 );
+
+DROP TABLE t1, t2;
+set max_join_size= @tmp_906385;
+
+

sql/sql_select.cc

@@ -21396,8 +21396,17 @@ void TABLE_LIST::print(THD *thd, table_map eliminated_tables, String *str,
   }
   else if (jtbm_subselect)
   {
-    if (jtbm_subselect->is_jtbm_const_tab)
+    if (jtbm_subselect->engine->engine_type() ==
+          subselect_engine::SINGLE_SELECT_ENGINE)
     {
+      /* 
+        We get here when conversion into materialization didn't finish (this
+        happens when
+        - The subquery is a degenerate case which produces 0 or 1 record
+        - subquery's optimization didn't finish because of @@max_join_size
+          limits
+        - ... maybe some other cases like this 
+      */
       str->append(STRING_WITH_LEN(" <materialize> ("));
       jtbm_subselect->engine->print(str, query_type);
       str->append(')');