From 8459bc4bcdf0403f8c9513dd4d1fed0840acafc1 Mon Sep 17 00:00:00 2001
From: David Rowley <dgrowley@gmail.com>
Date: Mon, 31 Oct 2022 10:05:12 +1300
Subject: [PATCH 3/3] Prefetch tuple memory during forward seqscans

---
 src/backend/access/heap/heapam.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 12be87efed..e8f1fc2d71 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -1025,6 +1025,17 @@ heapgettup_pagemode(HeapScanDesc scan,
 			tuple->t_len = ItemIdGetLength(lpp);
 			ItemPointerSet(&(tuple->t_self), page, lineoff);
 
+			/*
+			 * Prefetching the memory for the next tuple has shown to improve
+			 * performance on certain hardware.
+			 */
+			if (!backward && linesleft > 1)
+			{
+				lineoff = scan->rs_vistuples[lineindex + 1];
+				lpp = PageGetItemId(dp, lineoff);
+				pg_prefetch_mem(PageGetItem((Page) dp, lpp));
+			}
+
 			/*
 			 * if current tuple qualifies, return it.
 			 */
-- 
2.34.1