From 29c4ad98293e3c5cb3fcdd413a3f4904efff8762 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Fri, 1 Jan 2010 21:53:49 +0000 Subject: Support "x IS NOT NULL" clauses as indexscan conditions. This turns out to be just a minor extension of the previous patch that made "x IS NULL" indexable, because we can treat the IS NOT NULL condition as if it were "x < NULL" or "x > NULL" (depending on the index's NULLS FIRST/LAST option), just like IS NULL is treated like "x = NULL". Aside from any possible usefulness in its own right, this is an important improvement for index-optimized MAX/MIN aggregates: it is now reliably possible to get a column's min or max value cheaply, even when there are a lot of nulls cluttering the interesting end of the index. --- src/backend/access/gist/gistget.c | 22 ++++++++++++++-------- 1 file changed, 14 insertions(+), 8 deletions(-) (limited to 'src/backend/access/gist/gistget.c') diff --git a/src/backend/access/gist/gistget.c b/src/backend/access/gist/gistget.c index a094495b8a..98104a7a9f 100644 --- a/src/backend/access/gist/gistget.c +++ b/src/backend/access/gist/gistget.c @@ -8,7 +8,7 @@ * Portions Copyright (c) 1994, Regents of the University of California * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/access/gist/gistget.c,v 1.82 2009/10/08 22:34:57 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/access/gist/gistget.c,v 1.83 2010/01/01 21:53:49 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -413,14 +413,20 @@ gistindex_keytest(IndexTuple tuple, { /* * On non-leaf page we can't conclude that child hasn't NULL - * values because of assumption in GiST: uinon (VAL, NULL) is VAL - * But if on non-leaf page key IS NULL then all childs has NULL. + * values because of assumption in GiST: union (VAL, NULL) is VAL. + * But if on non-leaf page key IS NULL, then all children are NULL. */ - - Assert(key->sk_flags & SK_SEARCHNULL); - - if (GistPageIsLeaf(p) && !isNull) - return false; + if (key->sk_flags & SK_SEARCHNULL) + { + if (GistPageIsLeaf(p) && !isNull) + return false; + } + else + { + Assert(key->sk_flags & SK_SEARCHNOTNULL); + if (isNull) + return false; + } } else if (isNull) { -- cgit v1.2.1