Merge mysql-5.1 to mysql-5.5.

1 files changed, 31 insertions, 1 deletions

diff --git a/storage/innobase/include/page0page.ic b/storage/innobase/include/page0page.ic
index 115cee64f8b..c1a0ce73982 100644
--- a/storage/innobase/include/page0page.ic
+++ b/storage/innobase/include/page0page.ic
@@ -1,6 +1,6 @@
 /*****************************************************************************
 
-Copyright (c) 1994, 2009, Innobase Oy. All Rights Reserved.
+Copyright (c) 1994, 2011, Oracle and/or its affiliates. All Rights Reserved.
 
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
@@ -419,7 +419,37 @@ page_rec_is_infimum(
 	return(page_rec_is_infimum_low(page_offset(rec)));
 }
 
+/************************************************************//**
+Returns the nth record of the record list.
+This is the inverse function of page_rec_get_n_recs_before().
+@return	nth record */
+UNIV_INLINE
+rec_t*
+page_rec_get_nth(
+/*=============*/
+	page_t*	page,	/*!< in: page */
+	ulint	nth)	/*!< in: nth record */
+{
+	return((rec_t*) page_rec_get_nth_const(page, nth));
+}
+
 #ifndef UNIV_HOTBACKUP
+/************************************************************//**
+Returns the middle record of the records on the page. If there is an
+even number of records in the list, returns the first record of the
+upper half-list.
+@return	middle record */
+UNIV_INLINE
+rec_t*
+page_get_middle_rec(
+/*================*/
+	page_t*	page)	/*!< in: page */
+{
+	ulint	middle = (page_get_n_recs(page) + PAGE_HEAP_NO_USER_LOW) / 2;
+
+	return(page_rec_get_nth(page, middle));
+}
+
 /*************************************************************//**
 Compares a data tuple to a physical record. Differs from the function
 cmp_dtuple_rec_with_match in the way that the record must reside on an