From b2037afec14725e4521427edbee8071d04057a2d Mon Sep 17 00:00:00 2001 From: Alexander Korotkov Date: Sun, 8 Sep 2019 21:07:30 +0300 Subject: [PATCH] Fix handling Inf and Nan values in GiST pairing heap comparator Previously plain float comparison was used in GiST pairing heap. Such comparison doesn't provide proper ordering for value sets containing Inf and Nan values. This commit fixes that by usage of float8_cmp_internal(). Note, there is remaining problem with NULL distances, which are represented as Inf in pairing heap. It would be fixes in subsequent commit. Backpatch to all supported versions. Reported-by: Andrey Borodin Discussion: https://postgr.es/m/CAPpHfdsNvNdA0DBS%2BwMpFrgwT6C3-q50sFVGLSiuWnV3FqOJuQ%40mail.gmail.com Author: Alexander Korotkov Reviewed-by: Heikki Linnakangas Backpatch-through: 9.4 --- src/backend/access/gist/gistscan.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/src/backend/access/gist/gistscan.c b/src/backend/access/gist/gistscan.c index 12c74b982ca..2105ed604be 100644 --- a/src/backend/access/gist/gistscan.c +++ b/src/backend/access/gist/gistscan.c @@ -17,6 +17,7 @@ #include "access/gist_private.h" #include "access/gistscan.h" #include "access/relscan.h" +#include "utils/builtins.h" #include "utils/lsyscache.h" #include "utils/memutils.h" #include "utils/rel.h" @@ -36,8 +37,10 @@ pairingheap_GISTSearchItem_cmp(const pairingheap_node *a, const pairingheap_node /* Order according to distance comparison */ for (i = 0; i < scan->numberOfOrderBys; i++) { - if (sa->distances[i] != sb->distances[i]) - return (sa->distances[i] < sb->distances[i]) ? 1 : -1; + int cmp = -float8_cmp_internal(sa->distances[i], sb->distances[i]); + + if (cmp != 0) + return cmp; } /* Heap items go before inner pages, to ensure a depth-first search */