pgsql/src include/utils/tuplesort.h backend/ut ...

TODO updated:

* -Make NULL's come out at the beginning or end depending on the
ORDER BY direction (Tom)

CVSROOT: /home/projects/pgsql/cvsroot
Module name: pgsql
Changes by: tgl@hub.org 01/06/02 15:01:53

Modified files:
src/include/utils: tuplesort.h
src/backend/utils/sort: tuplesort.c
src/backend/commands: analyze.c

Log message:
Tweak sorting so that nulls appear at the front of a descending sort
(vs. at the end of a normal sort). This ensures that explicit sorts
yield the same ordering as a btree index scan. To be really sure that
that equivalence holds, we use the btree entries in pg_amop to decide
whether we are looking at a '<' or '>' operator. For a sort operator
that has no btree association, we put the nulls at the front if the
operator is named '>' ... pretty grotty, but it does the right thing in
simple ASC and DESC cases, and at least there's no possibility of getting
a different answer depending on the plan type chosen.

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