Add KNNGIST support to contrib/btree_gist.

This extends GiST's support for nearest-neighbor searches to many of the
standard data types.

Teodor Sigaev

1 files changed, 48 insertions, 1 deletions

diff --git a/contrib/btree_gist/btree_date.c b/contrib/btree_gist/btree_date.c
index 11904af2573..ccd7e2ad3f3 100644
--- a/contrib/btree_gist/btree_date.c
+++ b/contrib/btree_gist/btree_date.c
@@ -18,6 +18,7 @@ PG_FUNCTION_INFO_V1(gbt_date_compress);
 PG_FUNCTION_INFO_V1(gbt_date_union);
 PG_FUNCTION_INFO_V1(gbt_date_picksplit);
 PG_FUNCTION_INFO_V1(gbt_date_consistent);
+PG_FUNCTION_INFO_V1(gbt_date_distance);
 PG_FUNCTION_INFO_V1(gbt_date_penalty);
 PG_FUNCTION_INFO_V1(gbt_date_same);
 
@@ -25,6 +26,7 @@ Datum		gbt_date_compress(PG_FUNCTION_ARGS);
 Datum		gbt_date_union(PG_FUNCTION_ARGS);
 Datum		gbt_date_picksplit(PG_FUNCTION_ARGS);
 Datum		gbt_date_consistent(PG_FUNCTION_ARGS);
+Datum		gbt_date_distance(PG_FUNCTION_ARGS);
 Datum		gbt_date_penalty(PG_FUNCTION_ARGS);
 Datum		gbt_date_same(PG_FUNCTION_ARGS);
 
@@ -84,6 +86,17 @@ gbt_datekey_cmp(const void *a, const void *b)
 	return res;
 }
 
+static float8
+gdb_date_dist(const void *a, const void *b)
+{
+	/* we assume the difference can't overflow */
+	Datum diff = DirectFunctionCall2(date_mi,
+									 DateADTGetDatum(*((const DateADT *) a)),
+									 DateADTGetDatum(*((const DateADT *) b)));
+
+	return (float8) Abs(DatumGetInt32(diff));
+}
+
 
 static const gbtree_ninfo tinfo =
 {
@@ -94,10 +107,25 @@ static const gbtree_ninfo tinfo =
 	gbt_dateeq,
 	gbt_datele,
 	gbt_datelt,
-	gbt_datekey_cmp
+	gbt_datekey_cmp,
+	gdb_date_dist
 };
 
 
+PG_FUNCTION_INFO_V1(date_dist);
+Datum       date_dist(PG_FUNCTION_ARGS);
+Datum
+date_dist(PG_FUNCTION_ARGS)
+{
+	/* we assume the difference can't overflow */
+	Datum diff = DirectFunctionCall2(date_mi,
+									 PG_GETARG_DATUM(0),
+									 PG_GETARG_DATUM(1));
+
+	PG_RETURN_INT32(Abs(DatumGetInt32(diff)));
+}
+
+
 /**************************************************
  * date ops
  **************************************************/
@@ -140,6 +168,25 @@ gbt_date_consistent(PG_FUNCTION_ARGS)
 
 
 Datum
+gbt_date_distance(PG_FUNCTION_ARGS)
+{
+	GISTENTRY  *entry = (GISTENTRY *) PG_GETARG_POINTER(0);
+	DateADT		query = PG_GETARG_DATEADT(1);
+
+	/* Oid		subtype = PG_GETARG_OID(3); */
+	dateKEY    *kkk = (dateKEY *) DatumGetPointer(entry->key);
+	GBT_NUMKEY_R key;
+
+	key.lower = (GBT_NUMKEY *) &kkk->lower;
+	key.upper = (GBT_NUMKEY *) &kkk->upper;
+
+	PG_RETURN_FLOAT8(
+				   gbt_num_distance(&key, (void *) &query, GIST_LEAF(entry), &tinfo)
+		);
+}
+
+
+Datum
 gbt_date_union(PG_FUNCTION_ARGS)
 {
 	GistEntryVector *entryvec = (GistEntryVector *) PG_GETARG_POINTER(0);