Support ORDER BY ... NULLS FIRST/LAST, and add ASC/DESC/NULLS FIRST/NULLS LAST

per-column options for btree indexes.  The planner's support for this is still
pretty rudimentary; it does not yet know how to plan mergejoins with
nondefault ordering options.  The documentation is pretty rudimentary, too.
I'll work on improving that stuff later.

Note incompatible change from prior behavior: ORDER BY ... USING will now be
rejected if the operator is not a less-than or greater-than member of some
btree opclass.  This prevents less-than-sane behavior if an operator that
doesn't actually define a proper sort ordering is selected.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/test/regress/expected/point.out b/src/test/regress/expected/point.out
index 552be515d6f..96bcc6d695c 100644
--- a/src/test/regress/expected/point.out
+++ b/src/test/regress/expected/point.out
@@ -108,7 +108,7 @@ SELECT '' AS six, p.f1, p.f1 <-> point '(0,0)' AS dist
 SET geqo TO 'off';
 SELECT '' AS thirtysix, p1.f1 AS point1, p2.f1 AS point2, p1.f1 <-> p2.f1 AS dist
    FROM POINT_TBL p1, POINT_TBL p2
-   ORDER BY dist, point1 using <<, point2 using <<;
+   ORDER BY dist, p1.f1[0], p2.f1[0];
  thirtysix |   point1   |   point2   |       dist       
 -----------+------------+------------+------------------
            | (-10,0)    | (-10,0)    |                0
@@ -190,7 +190,7 @@ SELECT '' AS thirty, p1.f1 AS point1, p2.f1 AS point2
 SELECT '' AS fifteen, p1.f1 AS point1, p2.f1 AS point2, (p1.f1 <-> p2.f1) AS distance
    FROM POINT_TBL p1, POINT_TBL p2
    WHERE (p1.f1 <-> p2.f1) > 3 and p1.f1 << p2.f1
-   ORDER BY distance, point1 using <<, point2 using <<;
+   ORDER BY distance, p1.f1[0], p2.f1[0];
  fifteen |   point1   |   point2   |     distance     
 ---------+------------+------------+------------------
          | (-3,4)     | (0,0)      |                5