commit 8caa5026ffe6d14abe92cf5c3c442865ac663a01
Author: Alexander Korotkov <akorotkov@postgresql.org>
Date:   Mon Sep 2 07:36:35 2019 +0300

    Fix handling Inf and Nan values in GiST pairing heap comparator
    
    Reported-by:
    Bug:
    Discussion:
    Author:
    Reviewed-by:
    Tested-by:
    Backpatch-through:

diff --git a/src/backend/access/gist/gistscan.c b/src/backend/access/gist/gistscan.c
index 893d7765b6c..3bfeb18e2ed 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/float.h"
 #include "utils/lsyscache.h"
 #include "utils/memutils.h"
 #include "utils/rel.h"
@@ -36,8 +37,9 @@ 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 */
diff --git a/src/test/regress/expected/create_index.out b/src/test/regress/expected/create_index.out
index c6d575a2f99..117b11a1a63 100644
--- a/src/test/regress/expected/create_index.out
+++ b/src/test/regress/expected/create_index.out
@@ -523,16 +523,16 @@ SELECT * FROM point_tbl ORDER BY f1 <-> '0,1';
 SELECT * FROM point_tbl ORDER BY f1 <-> '0,1';
         f1         
 -------------------
- (10,10)
- (NaN,NaN)
  (0,0)
  (1e-300,-1e-300)
  (-3,4)
  (-10,0)
+ (10,10)
  (-5,-12)
  (5.1,34.5)
- 
  (1e+300,Infinity)
+ 
+ (NaN,NaN)
 (10 rows)
 
 EXPLAIN (COSTS OFF)
@@ -561,15 +561,15 @@ SELECT * FROM point_tbl WHERE f1 IS NOT NULL ORDER BY f1 <-> '0,1';
 SELECT * FROM point_tbl WHERE f1 IS NOT NULL ORDER BY f1 <-> '0,1';
         f1         
 -------------------
- (10,10)
- (NaN,NaN)
  (0,0)
  (1e-300,-1e-300)
  (-3,4)
  (-10,0)
+ (10,10)
  (-5,-12)
  (5.1,34.5)
  (1e+300,Infinity)
+ (NaN,NaN)
 (9 rows)
 
 EXPLAIN (COSTS OFF)