HA_CLUSTERED_INDEX

This patch introduces a index flag,
that will it possible to have optimizer consider
other indexes than primary key as clustered

see also: http://bugs.mysql.com/45458

---
 sql/handler.h     |    8 +++++++-
 sql/sql_select.cc |    3 ++-
 2 files changed, 9 insertions(+), 2 deletions(-)

Index: 70-spj/sql/handler.h
===================================================================
--- 70-spj.orig/sql/handler.h	2010-03-03 11:46:05.000000000 +0100
+++ 70-spj/sql/handler.h	2010-03-03 11:46:37.000000000 +0100
@@ -232,7 +232,13 @@ typedef Bitmap<HA_MAX_ALTER_FLAGS> HA_AL
   Index scan will not return records in rowid order. Not guaranteed to be
   set for unordered (e.g. HASH) indexes.
 */
-#define HA_KEY_SCAN_NOT_ROR     128 
+#define HA_KEY_SCAN_NOT_ROR     128
+
+/*
+  no IO if read data when scan index
+  i.e index is covering
+*/
+#define HA_CLUSTERED_INDEX      256
 
 /* operations for disable/enable indexes */
 #define HA_KEY_SWITCH_NONUNIQ      0
Index: 70-spj/sql/sql_select.cc
===================================================================
--- 70-spj.orig/sql/sql_select.cc	2010-03-03 11:46:05.000000000 +0100
+++ 70-spj/sql/sql_select.cc	2010-03-03 11:46:13.000000000 +0100
@@ -13478,7 +13478,8 @@ test_if_skip_sort_order(JOIN_TAB *tab,OR
 
         bool is_covering= table->covering_keys.is_set(nr) ||
                           (nr == table->s->primary_key &&
-                          table->file->primary_key_is_clustered());
+                          table->file->primary_key_is_clustered()) ||
+          test(table->file->index_flags(nr, 0, 0) & HA_CLUSTERED_INDEX);
 	
         /* 
           Don't use an index scan with ORDER BY without limit.