Improved code [skip ci]

src/hnswutils.c

@@ -805,6 +805,12 @@ HnswLoadUnvisitedFromDisk(HnswElement element, HnswUnvisited * unvisited, int *u
 		if (!found)
 			unvisited[(*unvisitedLength)++].indextid = *indextid;
 	}
+
+#ifdef USE_PREFETCH
+	/* TODO limit by get_tablespace_io_concurrency */
+	for (int i = 0; i < *unvisitedLength; i++)
+		PrefetchBuffer(index, MAIN_FORKNUM, ItemPointerGetBlockNumber(&unvisited[i].indextid));
+#endif
 }
 
 /*