diff --git a/src/backend/utils/adt/varchar.c b/src/backend/utils/adt/varchar.c
new file mode 100644
index 502ca44..284b5d1
*** a/src/backend/utils/adt/varchar.c
--- b/src/backend/utils/adt/varchar.c
*************** bpcharcmp(PG_FUNCTION_ARGS)
*** 846,851 ****
--- 846,863 ----
  				len2;
  	int			cmp;
  
+ 	/*
+ 	 * Trimming trailing spaces off of both strings can cause a string
+ 	 * with a character less than a space to compare greater than a
+ 	 * space-extended string, e.g. this returns false:
+ 	 *		SELECT E'ab\n'::CHAR(10) < E'ab '::CHAR(10);
+ 	 * even though '\n' is less than the space if CHAR(10) was
+ 	 * space-extended.  The correct solution would be to trim only
+ 	 * the longer string to be the same length of the shorter, if
+ 	 * possible, then do the comparison.  However, changing this
+ 	 * might break existing indexes, breaking binary upgrades.
+ 	 * For details, see http://www.postgresql.org/message-id/CAK+WP1xdmyswEehMuetNztM4H199Z1w9KWRHVMKzyyFM+hV=zA@mail.gmail.com
+ 	 */
  	len1 = bcTruelen(arg1);
  	len2 = bcTruelen(arg2);