From: Paul Ramsey <pramsey@cleverelephant.ca>
Date: Sun, 15 Nov 2009 19:23:21 +0000 (+0000)
Subject: Make the _cmp and _eq methods use the same equality conditions so that
X-Git-Tag: 1.5.0b1~246
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=876c48433a4c40f42458e7067a4e362fdbe40ee1;p=postgis

Make the _cmp and _eq methods use the same equality conditions so that
indexed and unindexed answers will be the same. (#292)


git-svn-id: http://svn.osgeo.org/postgis/trunk@4814 b70326c6-7e19-0410-871a-916f4a2858ee
---

diff --git a/postgis/geography_btree.c b/postgis/geography_btree.c
index a6d24fae4..f806f3cfc 100644
--- a/postgis/geography_btree.c
+++ b/postgis/geography_btree.c
@@ -26,14 +26,6 @@ Datum geography_gt(PG_FUNCTION_ARGS);
 Datum geography_cmp(PG_FUNCTION_ARGS);
 
 
-/*
-** Calculate a hash code based on the geometry data alone
-*/
-static uint32 geography_hash(GSERIALIZED *g)
-{
-	return DatumGetUInt32(hash_any((void*)g, VARSIZE(g)));
-}
-
 /*
 ** Utility function to return the center point of a 
 ** geocentric bounding box. We don't divide by two 
@@ -166,16 +158,27 @@ Datum geography_ge(PG_FUNCTION_ARGS)
 	PG_RETURN_BOOL(FALSE);	
 }
 
+
+#if 0
+/*
+** Calculate a hash code based on the geometry data alone
+*/
+static uint32 geography_hash(GSERIALIZED *g)
+{
+	return DatumGetUInt32(hash_any((void*)g, VARSIZE(g)));
+}
 /*
 ** BTree support function. Based on two geographies return true if
-** they are "equal" and false otherwise.
+** they are "equal" and false otherwise. This version uses a hash
+** function to try and shoot for a more exact equality test.
 */
 PG_FUNCTION_INFO_V1(geography_eq);
 Datum geography_eq(PG_FUNCTION_ARGS)
 {
-	/* Put aside some stack memory and use it for GIDX pointers. */
+	/* Perfect equals test based on hash */
 	GSERIALIZED *g1 = (GSERIALIZED*)PG_DETOAST_DATUM(PG_GETARG_DATUM(0));
 	GSERIALIZED *g2 = (GSERIALIZED*)PG_DETOAST_DATUM(PG_GETARG_DATUM(1));
+
 	uint32 h1 = geography_hash(g1);
 	uint32 h2 = geography_hash(g2);
 
@@ -185,7 +188,39 @@ Datum geography_eq(PG_FUNCTION_ARGS)
 	if( h1 == h2 )
 		PG_RETURN_BOOL(TRUE);	
 		
+	PG_RETURN_BOOL(FALSE); 
+}
+#endif
+
+/*
+** BTree support function. Based on two geographies return true if
+** they are "equal" and false otherwise.
+*/
+PG_FUNCTION_INFO_V1(geography_eq);
+Datum geography_eq(PG_FUNCTION_ARGS)
+{
+	/* Put aside some stack memory and use it for GIDX pointers. */
+	char gboxmem1[GIDX_MAX_SIZE];
+	char gboxmem2[GIDX_MAX_SIZE];
+	GIDX *gbox1 = (GIDX*)gboxmem1;
+	GIDX *gbox2 = (GIDX*)gboxmem2;
+	POINT3D p1, p2;
+
+	/* Must be able to build box for each argument (ie, not empty geometry) */
+	if( ! geography_datum_gidx(PG_GETARG_DATUM(0), gbox1) ||
+	    ! geography_datum_gidx(PG_GETARG_DATUM(1), gbox2) )
+	{
+		PG_RETURN_BOOL(FALSE);
+	}
+	
+	geography_gidx_center(gbox1, &p1);
+	geography_gidx_center(gbox2, &p2);
+	
+	if( FP_EQUALS(p1.x, p2.x) && FP_EQUALS(p1.y, p2.y) && FP_EQUALS(p1.z, p2.z) ) 
+		PG_RETURN_BOOL(TRUE);	
+	
 	PG_RETURN_BOOL(FALSE);	
+
 }
 
 /*