branches/zip:

Add a NOTE to the comment of btr_node_ptr_get_child_page_no()
to prevent mysterious bugs.

include/btr0btr.h

@@ -193,6 +193,10 @@ btr_leaf_page_release(
 	mtr_t*		mtr);		/*!< in: mtr */
 /**************************************************************//**
 Gets the child node file address in a node pointer.
+NOTE: the offsets array must contain all offsets for the record since
+we read the last field according to offsets and assume that it contains
+the child page number. In other words offsets must have been retrieved
+with rec_get_offsets(n_fields=ULINT_UNDEFINED).
 @return	child node address */
 UNIV_INLINE
 ulint

include/btr0btr.ic

@@ -255,6 +255,10 @@ btr_page_set_prev(
 
 /**************************************************************//**
 Gets the child node file address in a node pointer.
+NOTE: the offsets array must contain all offsets for the record since
+we read the last field according to offsets and assume that it contains
+the child page number. In other words offsets must have been retrieved
+with rec_get_offsets(n_fields=ULINT_UNDEFINED).
 @return	child node address */
 UNIV_INLINE
 ulint