1 files changed, 31 insertions, 8 deletions

diff --git a/sql/sql_select.h b/sql/sql_select.h
index c50303ee812..285019b4a5c 100644
--- a/sql/sql_select.h
+++ b/sql/sql_select.h
@@ -95,6 +95,10 @@ typedef struct st_table_ref
 } TABLE_REF;
 
 
+
+#define CACHE_BLOB      1        /* blob field  */
+#define CACHE_STRIPPED  2        /* field stripped of trailing spaces */
+
 /**
   CACHE_FIELD and JOIN_CACHE is used on full join to cache records in outer
   table
@@ -103,8 +107,8 @@ typedef struct st_table_ref
 typedef struct st_cache_field {
   uchar *str;
   uint length, blob_length;
-  Field_blob *blob_field;
-  bool strip;
+  Field *field;
+  uint type;    /**< category of the of the copied field (CACHE_BLOB et al.) */
 } CACHE_FIELD;
 
 
@@ -362,7 +366,25 @@ public:
   */
   bool no_const_tables; 
   
-  JOIN *tmp_join; ///< copy of this JOIN to be used with temporary tables
+  /**
+    Copy of this JOIN to be used with temporary tables.
+
+    tmp_join is used when the JOIN needs to be "reusable" (e.g. in a subquery
+    that gets re-executed several times) and we know will use temporary tables
+    for materialization. The materialization to a temporary table overwrites the
+    JOIN structure to point to the temporary table after the materialization is
+    done. This is where tmp_join is used : it's a copy of the JOIN before the
+    materialization and is used in restoring before re-execution by overwriting
+    the current JOIN structure with the saved copy.
+    Because of this we should pay extra care of not freeing up helper structures
+    that are referenced by the original contents of the JOIN. We can check for
+    this by making sure the "current" join is not the temporary copy, e.g.
+    !tmp_join || tmp_join != join
+ 
+    We should free these sub-structures at JOIN::destroy() if the "current" join
+    has a copy is not that copy.
+  */
+  JOIN *tmp_join;
   ROLLUP rollup;				///< Used with rollup
 
   bool select_distinct;				///< Set if SELECT DISTINCT
@@ -727,10 +749,11 @@ public:
      we need to check for errors executing it and react accordingly
     */
     if (!res && table->in_use->is_error())
-      res= 2;
+      res= 1; /* STORE_KEY_FATAL */
     dbug_tmp_restore_column_map(table->write_set, old_map);
     null_key= to_field->is_null() || item->null_value;
-    return (err != 0 || res > 2 ? STORE_KEY_FATAL : (store_key_result) res); 
+    return ((err != 0 || res < 0 || res > 2) ? STORE_KEY_FATAL : 
+            (store_key_result) res);
   }
 };
 
@@ -759,17 +782,17 @@ protected:
       if ((res= item->save_in_field(to_field, 1)))
       {       
         if (!err)
-          err= res;
+          err= res < 0 ? 1 : res; /* 1=STORE_KEY_FATAL */
       }
       /*
         Item::save_in_field() may call Item::val_xxx(). And if this is a subquery
         we need to check for errors executing it and react accordingly
         */
       if (!err && to_field->table->in_use->is_error())
-        err= 2;
+        err= 1; /* STORE_KEY_FATAL */
     }
     null_key= to_field->is_null() || item->null_value;
-    return (err > 2 ?  STORE_KEY_FATAL : (store_key_result) err);
+    return (err > 2 ? STORE_KEY_FATAL : (store_key_result) err);
   }
 };