Add support for <-> (box, point) operator to GiST box_ops

Index-based calculation of this operator is exact.  So, signature of
gist_bbox_distance() function is changes so that caller is responsible for
setting *recheck flag.

Discussion: https://postgr.es/m/f71ba19d-d989-63b6-f04a-abf02ad9345d%40postgrespro.ru
Author: Nikita Glukhov
Reviewed-by: Tom Lane, Alexander Korotkov

1 files changed, 31 insertions, 17 deletions

diff --git a/src/backend/access/gist/gistproc.c b/src/backend/access/gist/gistproc.c
index 1826b51bbb..118dd9653f 100644
--- a/src/backend/access/gist/gistproc.c
+++ b/src/backend/access/gist/gistproc.c
@@ -1464,26 +1464,12 @@ gist_point_distance(PG_FUNCTION_ARGS)
 	PG_RETURN_FLOAT8(distance);
 }
 
-/*
- * The inexact GiST distance method for geometric types that store bounding
- * boxes.
- *
- * Compute lossy distance from point to index entries.  The result is inexact
- * because index entries are bounding boxes, not the exact shapes of the
- * indexed geometric types.  We use distance from point to MBR of index entry.
- * This is a lower bound estimate of distance from point to indexed geometric
- * type.
- */
 static float8
-gist_bbox_distance(GISTENTRY *entry, Datum query,
-				   StrategyNumber strategy, bool *recheck)
+gist_bbox_distance(GISTENTRY *entry, Datum query, StrategyNumber strategy)
 {
 	float8		distance;
 	StrategyNumber strategyGroup = strategy / GeoStrategyNumberOffset;
 
-	/* Bounding box distance is always inexact. */
-	*recheck = true;
-
 	switch (strategyGroup)
 	{
 		case PointStrategyNumberGroup:
@@ -1500,6 +1486,32 @@ gist_bbox_distance(GISTENTRY *entry, Datum query,
 }
 
 Datum
+gist_box_distance(PG_FUNCTION_ARGS)
+{
+	GISTENTRY  *entry = (GISTENTRY *) PG_GETARG_POINTER(0);
+	Datum		query = PG_GETARG_DATUM(1);
+	StrategyNumber strategy = (StrategyNumber) PG_GETARG_UINT16(2);
+
+	/* Oid subtype = PG_GETARG_OID(3); */
+	/* bool	   *recheck = (bool *) PG_GETARG_POINTER(4); */
+	float8		distance;
+
+	distance = gist_bbox_distance(entry, query, strategy);
+
+	PG_RETURN_FLOAT8(distance);
+}
+
+/*
+ * The inexact GiST distance methods for geometric types that store bounding
+ * boxes.
+ *
+ * Compute lossy distance from point to index entries.  The result is inexact
+ * because index entries are bounding boxes, not the exact shapes of the
+ * indexed geometric types.  We use distance from point to MBR of index entry.
+ * This is a lower bound estimate of distance from point to indexed geometric
+ * type.
+ */
+Datum
 gist_circle_distance(PG_FUNCTION_ARGS)
 {
 	GISTENTRY  *entry = (GISTENTRY *) PG_GETARG_POINTER(0);
@@ -1510,7 +1522,8 @@ gist_circle_distance(PG_FUNCTION_ARGS)
 	bool	   *recheck = (bool *) PG_GETARG_POINTER(4);
 	float8		distance;
 
-	distance = gist_bbox_distance(entry, query, strategy, recheck);
+	distance = gist_bbox_distance(entry, query, strategy);
+	*recheck = true;
 
 	PG_RETURN_FLOAT8(distance);
 }
@@ -1526,7 +1539,8 @@ gist_poly_distance(PG_FUNCTION_ARGS)
 	bool	   *recheck = (bool *) PG_GETARG_POINTER(4);
 	float8		distance;
 
-	distance = gist_bbox_distance(entry, query, strategy, recheck);
+	distance = gist_bbox_distance(entry, query, strategy);
+	*recheck = true;
 
 	PG_RETURN_FLOAT8(distance);
 }