bug #251 - destroyed object reused - fixed

sql/field.h

@@ -134,6 +134,7 @@ class Field
   virtual void sort_string(char *buff,uint length)=0;
   virtual bool optimize_range(uint idx);
   virtual bool store_for_compare() { return 0; }
+  virtual void free() {}
   Field *new_field(MEM_ROOT *root, struct st_table *new_table)
   {
     Field *tmp= (Field*) memdup_root(root,(char*) this,size_of());
@@ -937,7 +938,7 @@ class Field_blob :public Field_str {
   int pack_cmp(const char *b, uint key_length);
   uint packed_col_length(const char *col_ptr, uint length);
   uint max_packed_col_length(uint max_length);
-  inline void free() { value.free(); }
+  void free() { value.free(); }
   inline void clear_temporary() { bzero((char*) &value,sizeof(value)); }
   friend void field_conv(Field *to,Field *from);
   uint size_of() const { return sizeof(*this); }

sql/sql_select.cc

@@ -4791,7 +4791,7 @@ free_tmp_table(THD *thd, TABLE *entry)
     (void) ha_delete_table(entry->db_type,entry->real_name);
   /* free blobs */
   for (Field **ptr=entry->field ; *ptr ; ptr++)
-    delete *ptr;
+    (*ptr)->free();
   my_free((gptr) entry->record[0],MYF(0));
   free_io_cache(entry);