From 2904324a88f672b2ecc22735279c16d6e1ee178c Mon Sep 17 00:00:00 2001 From: Heikki Linnakangas Date: Tue, 1 Apr 2025 13:24:27 +0300 Subject: [PATCH] heapam: Only set tuple's block once per page in pagemode Due to splitting the block id into two 16 bit integers, BlockIdSet() is more expensive than one might think. Doing it once per returned tuple shows up as a small but reliably reproducible cost. It's simple enough to set the block number just once per block in pagemode, so do so. Author: Andres Freund Discussion: https://www.postgresql.org/message-id/lxzj26ga6ippdeunz6kuncectr5gfuugmm2ry22qu6hcx6oid6@lzx3sjsqhmt6 --- src/backend/access/heap/heapam.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c index 6e433db039e..cedaa195cb6 100644 --- a/src/backend/access/heap/heapam.c +++ b/src/backend/access/heap/heapam.c @@ -1052,6 +1052,9 @@ heapgettup_pagemode(HeapScanDesc scan, linesleft = scan->rs_ntuples; lineindex = ScanDirectionIsForward(dir) ? 0 : linesleft - 1; + /* block is the same for all tuples, set it once outside the loop */ + ItemPointerSetBlockNumber(&tuple->t_self, scan->rs_cblock); + /* lineindex now references the next or previous visible tid */ continue_page: @@ -1067,7 +1070,7 @@ continue_page: tuple->t_data = (HeapTupleHeader) PageGetItem(page, lpp); tuple->t_len = ItemIdGetLength(lpp); - ItemPointerSet(&(tuple->t_self), scan->rs_cblock, lineoff); + ItemPointerSetOffsetNumber(&tuple->t_self, lineoff); /* skip any tuples that don't match the scan key */ if (key != NULL &&