From: Sandro Santilli <strk@keybit.net>
Date: Fri, 31 Jul 2015 17:23:29 +0000 (+0000)
Subject: Add memcmp short-circuit to ST_Equals (#3223)
X-Git-Tag: 2.2.0rc1~200
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=66d1d5f9c2f5cf186f62a4c638ada2c1b34ef962;p=postgis

Add memcmp short-circuit to ST_Equals (#3223)

Patch by Daniel Baston

git-svn-id: http://svn.osgeo.org/postgis/trunk@13864 b70326c6-7e19-0410-871a-916f4a2858ee
---

diff --git a/NEWS b/NEWS
index 781b5d8d9..b549b7ea0 100644
--- a/NEWS
+++ b/NEWS
@@ -96,6 +96,7 @@ PostGIS 2.2.0
 
  * Enhancements *
 
+  - #3223, Add memcmp short-circuit to ST_Equals (Daniel Baston)
   - #2278, Make liblwgeom compatible between minor releases
   - #897, ST_AsX3D support for GeoCoordinates and systems "GD" "WE"
            ability to flip x/y axis (use option = 2, 3)
diff --git a/postgis/lwgeom_geos.c b/postgis/lwgeom_geos.c
index 2e57e09c1..245ab5fd1 100644
--- a/postgis/lwgeom_geos.c
+++ b/postgis/lwgeom_geos.c
@@ -3097,6 +3097,14 @@ Datum ST_Equals(PG_FUNCTION_ARGS)
 		}
 	}
 
+	/*
+	 * short-circuit: if geom1 and geom2 are binary-equivalent, we can return
+	 * TRUE.  This is much faster than doing the comparison using GEOS.
+	 */
+	if (VARSIZE(geom1) == VARSIZE(geom2) && !memcmp(geom1, geom2, VARSIZE(geom1))) {
+	    PG_RETURN_BOOL(TRUE);
+	}
+
 	initGEOS(lwpgnotice, lwgeom_geos_error);
 
 	g1 = (GEOSGeometry *)POSTGIS2GEOS(geom1);