From c2f586ac7d3613f2053c32a911d0e52fb8975151 Mon Sep 17 00:00:00 2001
From: Paul Ramsey <pramsey@cleverelephant.ca>
Date: Thu, 23 Apr 2015 18:20:00 +0000
Subject: [PATCH] #3018, GROUP BY geography sometimes returns duplicate rows

git-svn-id: http://svn.osgeo.org/postgis/trunk@13437 b70326c6-7e19-0410-871a-916f4a2858ee
---
 NEWS                      |  1 +
 postgis/geography_btree.c | 30 +++++++++++++++++++++++++-----
 2 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/NEWS b/NEWS
index 7da25d146..457eca201 100644
--- a/NEWS
+++ b/NEWS
@@ -96,6 +96,7 @@ PostGIS 2.2.0
   - #3061, Allow duplicate points in JSON, GML, GML ST_GeomFrom* functions
   - #3086, ST_DumpValues() crashes backend on cleanup with invalid
            band indexes
+  - #3018, GROUP BY geography sometimes returns duplicate rows
 
  * Code refactoring *
 
diff --git a/postgis/geography_btree.c b/postgis/geography_btree.c
index dd3da7969..23b59e064 100644
--- a/postgis/geography_btree.c
+++ b/postgis/geography_btree.c
@@ -210,7 +210,7 @@ Datum geography_eq(PG_FUNCTION_ARGS)
 
 	/* Must be able to build box for each argument (ie, not empty geometry) */
 	if ( ! gserialized_datum_get_gidx_p(PG_GETARG_DATUM(0), gbox1) ||
-	        ! gserialized_datum_get_gidx_p(PG_GETARG_DATUM(1), gbox2) )
+	     ! gserialized_datum_get_gidx_p(PG_GETARG_DATUM(1), gbox2) )
 	{
 		PG_RETURN_BOOL(FALSE);
 	}
@@ -249,13 +249,33 @@ Datum geography_cmp(PG_FUNCTION_ARGS)
 	geography_gidx_center(gbox1, &p1);
 	geography_gidx_center(gbox2, &p2);
 
-	if ( p1.x > p2.x && p1.y > p2.y && p1.z > p2.z )
+	if  ( ! FP_EQUALS(p1.x, p2.x) )
+	{
+		if  (p1.x < p2.x)
+		{
+			PG_RETURN_INT32(-1);
+		}
 		PG_RETURN_INT32(1);
+	}
 
-	if ( FP_EQUALS(p1.x, p2.x) && FP_EQUALS(p1.y, p2.y) && FP_EQUALS(p1.z, p2.z) )
-		PG_RETURN_INT32(0);
+	if  ( ! FP_EQUALS(p1.y, p2.y) )
+	{
+		if  (p1.y < p2.y)
+		{
+			PG_RETURN_INT32(-1);
+		}
+		PG_RETURN_INT32(1);
+	}
 
-	PG_RETURN_INT32(-1);
+	if  ( ! FP_EQUALS(p1.z, p2.z) )
+	{
+		if  (p1.z < p2.z)
+		{
+			PG_RETURN_INT32(-1);
+		}
+		PG_RETURN_INT32(1);
+	}
 
+	PG_RETURN_INT32(0);
 }
 
-- 
2.40.0