Merge rurik.mysql.com:/home/igor/mysql-5.0

into rurik.mysql.com:/home/igor/dev/mysql-5.0-0


sql/item.h:
  Auto merged
sql/sql_select.cc:
  Auto merged

4 files changed, 17 insertions, 19 deletions

diff --git a/sql/item.cc b/sql/item.cc
index 46fbaf2ed85..73c8e80228b 100644
--- a/sql/item.cc
+++ b/sql/item.cc
@@ -2978,41 +2978,38 @@ Item *Item_field::set_no_const_sub(byte *arg)
 
 
 /*
-  Set a pointer to the multiple equality the field reference belongs to
+  Replace an Item_field for an equal Item_field that evaluated earlier
   (if any)
    
   SYNOPSIS
-    replace_equal_field_processor()
+    replace_equal_field_()
     arg - a dummy parameter, is not used here
   
   DESCRIPTION
-    The function replaces a pointer to a field in the Item_field object
-    by a pointer to another field.
-    The replacement field is taken from the very beginning of
-    the item_equal list which the Item_field object refers to (belongs to)  
-    If the Item_field object does not refer any Item_equal object,
-    nothing is done.
+    The function returns a pointer to an item that is taken from
+    the very beginning of the item_equal list which the Item_field
+    object refers to (belongs to).  
+    If the Item_field object does not refer any Item_equal object
+    'this' is returned 
 
   NOTES
     This function is supposed to be called as a callback parameter in calls
-    of the walk method.  
+    of the thransformer method.  
 
   RETURN VALUES
-    0 
+    pointer to a replacement Item_field if there is a better equal item;
+    this - otherwise.
 */
 
-bool Item_field::replace_equal_field_processor(byte *arg)
+Item *Item_field::replace_equal_field(byte *arg)
 {
   if (item_equal)
   {
     Item_field *subst= item_equal->get_first();
     if (!field->eq(subst->field))
-    {
-      field= subst->field;
-      return 0;
-    }
+      return subst;
   }
-  return 0;
+  return this;
 }
 
 
diff --git a/sql/item.h b/sql/item.h
index f7bb98bb8ad..e86c66ca6f3 100644
--- a/sql/item.h
+++ b/sql/item.h
@@ -520,7 +520,7 @@ public:
   virtual bool collect_item_field_processor(byte * arg) { return 0; }
   virtual Item *equal_fields_propagator(byte * arg) { return this; }
   virtual Item *set_no_const_sub(byte *arg) { return this; }
-  virtual bool replace_equal_field_processor(byte * arg) { return 0; }
+  virtual Item *replace_equal_field(byte * arg) { return this; }
   
   virtual Item *this_item() { return this; } /* For SPs mostly. */
   virtual Item *this_const_item() const { return const_cast<Item*>(this); } /* For SPs mostly. */
@@ -754,7 +754,7 @@ public:
   Item_equal *find_item_equal(COND_EQUAL *cond_equal);
   Item *equal_fields_propagator(byte *arg);
   Item *set_no_const_sub(byte *arg);
-  bool replace_equal_field_processor(byte *arg);
+  Item *replace_equal_field(byte *arg);
   inline uint32 max_disp_length() { return field->max_length(); }
   Item_field *filed_for_view_update() { return this; }
   Item *safe_charset_converter(CHARSET_INFO *tocs);
diff --git a/sql/item_subselect.h b/sql/item_subselect.h
index 56864109a04..1a407c695b2 100644
--- a/sql/item_subselect.h
+++ b/sql/item_subselect.h
@@ -96,6 +96,7 @@ public:
   virtual bool exec();
   virtual void fix_length_and_dec();
   table_map used_tables() const;
+  table_map not_null_tables() const { return 0; }
   bool const_item() const;
   inline table_map get_used_tables_cache() { return used_tables_cache; }
   inline bool get_const_item_cache() { return const_item_cache; }
diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index a54294f00c0..f380876577a 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -7054,7 +7054,7 @@ static COND* substitute_for_best_equal_field(COND *cond,
     return eliminate_item_equal(0, cond_equal, item_equal);
   }
   else
-    cond->walk(&Item::replace_equal_field_processor, 0);
+    cond->transform(&Item::replace_equal_field, 0);
   return cond;
 }