Make index_merge code call handler::extra(HA_EXTRA_RETRIEVE_PRIMARY_KEY) if it

will call handler::position() during key scan. 
Undo the previous, less efficient fix (cset 2004-11-30 19:56:25+02:00, heikki@hundin.mysql.fi)

innobase/include/row0mysql.h

@@ -549,10 +549,7 @@ struct row_prebuilt_struct {
 					format */
 	ulint		hint_need_to_fetch_extra_cols;
 					/* normally this is set to 0; if this
-					is set to ROW_RETRIEVE_PRIMARY_KEY
-					(that value is obsolete starting from
-					5.0.2, because we always fetch the
-					primary key cols),
+					is set to ROW_RETRIEVE_PRIMARY_KEY,
 					then we should at least retrieve all
 					columns in the primary key; if this
 					is set to ROW_RETRIEVE_ALL_COLS, then
@@ -625,9 +622,6 @@ struct row_prebuilt_struct {
 
 /* Values for hint_need_to_fetch_extra_cols */
 #define ROW_RETRIEVE_PRIMARY_KEY	1
-					/* value 1 is obsolete starting from
-					5.0.2, because we always fetch the
-					primary key cols */
 #define ROW_RETRIEVE_ALL_COLS		2
 
 

sql/ha_innodb.cc

@@ -2275,13 +2275,7 @@ build_template(
 	ulint		n_fields;
 	ulint		n_requested_fields	= 0;
 	ibool		fetch_all_in_key	= FALSE;
-	ibool		fetch_primary_key_cols	= TRUE; /* The ROR code in
-						opt_range.cc assumes that the
-						primary key cols are always
-						retrieved. Starting from
-						MySQL-5.0.2, let us always
-						fetch them, even though it
-						wastes some CPU. */ 
+	ibool		fetch_primary_key_cols	= FALSE;
 	ulint		i;
 
 	if (prebuilt->select_lock_type == LOCK_X) {

sql/opt_range.cc

@@ -897,7 +897,7 @@ int QUICK_RANGE_SELECT::init_ror_merged_scan(bool reuse_handler)
   {
     DBUG_PRINT("info", ("Reusing handler %p", file));
     if (file->extra(HA_EXTRA_KEYREAD) ||
-        file->extra(HA_EXTRA_RETRIEVE_ALL_COLS) |
+        file->extra(HA_EXTRA_RETRIEVE_PRIMARY_KEY) ||
         init() || reset())
     {
       DBUG_RETURN(1);
@@ -922,7 +922,7 @@ int QUICK_RANGE_SELECT::init_ror_merged_scan(bool reuse_handler)
   }
 
   if (file->extra(HA_EXTRA_KEYREAD) ||
-      file->extra(HA_EXTRA_RETRIEVE_ALL_COLS) ||
+      file->extra(HA_EXTRA_RETRIEVE_PRIMARY_KEY) ||
       init() || reset())
   {
     file->close();
@@ -5600,7 +5600,8 @@ int QUICK_INDEX_MERGE_SELECT::read_keys_and_merge()
   DBUG_ENTER("QUICK_INDEX_MERGE_SELECT::prepare_unique");
 
   /* We're going to just read rowids. */
-  head->file->extra(HA_EXTRA_KEYREAD);
+  if (head->file->extra(HA_EXTRA_KEYREAD))
+    DBUG_RETURN(1);
 
   /*
     Make innodb retrieve all PK member fields, so
@@ -5609,7 +5610,8 @@ int QUICK_INDEX_MERGE_SELECT::read_keys_and_merge()
     (This also creates a deficiency - it is possible that we will retrieve
      parts of key that are not used by current query at all.)
   */
-  head->file->extra(HA_EXTRA_RETRIEVE_ALL_COLS);
+  if (head->file->extra(HA_EXTRA_RETRIEVE_PRIMARY_KEY))
+    DBUG_RETURN(1);
 
   cur_quick_it.rewind();
   cur_quick= cur_quick_it++;