Fixed bug mdev-10736 that caused crashes.

The bug manifested itself for recursive definitions that
used anchors over tables with blobs.

mysql-test/r/cte_recursive.result

@@ -1623,3 +1623,12 @@ n
 3
 4
 5
+#
+# MDEV-10736: recursive definition with anchor over a table with blob
+#
+CREATE TABLE t1 (f VARCHAR(1024));
+WITH RECURSIVE cte(f) AS
+(SELECT t1.f FROM t1 UNION ALL SELECT cte.f FROM cte) 
+SELECT * FROM cte;
+f
+DROP TABLE t1;

mysql-test/t/cte_recursive.test

@@ -1184,3 +1184,13 @@ drop table t1;
 WITH RECURSIVE cte(n) AS
   ( SELECT n+1 FROM cte WHERE n < 5 UNION SELECT 1 UNION SELECT 1 )
 SELECT * FROM cte;
+
+--echo #
+--echo # MDEV-10736: recursive definition with anchor over a table with blob
+--echo #
+
+CREATE TABLE t1 (f VARCHAR(1024));
+WITH RECURSIVE cte(f) AS
+(SELECT t1.f FROM t1 UNION ALL SELECT cte.f FROM cte) 
+SELECT * FROM cte;
+DROP TABLE t1;

sql/sql_cte.cc

@@ -1301,6 +1301,9 @@ bool With_element::instantiate_tmp_tables()
                               &rec_result->tmp_table_param.recinfo,
                               0))
       return true;
+
+    rec_table->file->extra(HA_EXTRA_WRITE_CACHE);
+    rec_table->file->extra(HA_EXTRA_IGNORE_DUP_KEY);
   }
   return false;
 }

sql/sql_union.cc

@@ -237,12 +237,6 @@ select_union_recursive::create_result_table(THD *thd_arg,
   for (uint i=0; i < table->s->fields; i++)
     rec_table->field[i]->flags &= ~PART_KEY_FLAG;
 
-  if (create_table)
-  {
-    rec_table->file->extra(HA_EXTRA_WRITE_CACHE);
-    rec_table->file->extra(HA_EXTRA_IGNORE_DUP_KEY);
-  }
-
   if (rec_tables.push_back(rec_table))
     return true;