Added bound option [skip ci]

src/ivfflat.c

@@ -13,6 +13,7 @@
 #endif
 
 int			ivfflat_probes;
+int			ivfflat_bound;
 static relopt_kind ivfflat_relopt_kind;
 
 /*
@@ -32,6 +33,10 @@ _PG_init(void)
 	DefineCustomIntVariable("ivfflat.probes", "Sets the number of probes",
 							"Valid range is 1..lists.", &ivfflat_probes,
 							1, 1, IVFFLAT_MAX_LISTS, PGC_USERSET, 0, NULL, NULL, NULL);
+
+	DefineCustomIntVariable("ivfflat.bound", "Sets the max results from index (experimental)",
+							NULL, &ivfflat_bound,
+							0, 0, INT_MAX, PGC_USERSET, 0, NULL, NULL, NULL);
 }
 
 /*

src/ivfflat.h

@@ -78,6 +78,7 @@
 
 /* Variables */
 extern int	ivfflat_probes;
+extern int	ivfflat_bound;
 
 /* Exported functions */
 PGDLLEXPORT void _PG_init(void);

src/ivfscan.c

@@ -126,6 +126,10 @@ GetScanItems(IndexScanDesc scan, Datum value)
 	 */
 	BufferAccessStrategy bas = GetAccessStrategy(BAS_BULKREAD);
 
+	/* Set the max number of results */
+	if (ivfflat_bound > 0)
+		tuplesort_set_bound(so->sortstate, ivfflat_bound);
+
 	/* Search closest probes lists */
 	while (!pairingheap_is_empty(so->listQueue))
 	{