From 512d3e8919b649d36a6f246c657c8b8df7536e8a Mon Sep 17 00:00:00 2001 From: Melanie Plageman Date: Fri, 11 Sep 2026 20:37:53 -0400 Subject: [PATCH] Make on-access pruning pin visibility map before locking heap page b46e1e54d078 pinned the VM after acquiring a cleanup lock on the heap page when on-access pruning. This was not correct, as pinning the VM may require I/O. Pin the VM before acquiring the lock. This could mean occasional unneeded pinning when the buffer is under contention, but that should be rare. Reported-by: Melanie Plageman Reviewed-by: Chao Li Discussion: https://postgr.es/m/CAAKRu_aR6e2mNVo-DNHDUfBE5i0cbE4%3Du%3D_Qi9%2Bv573qiGtBig%40mail.gmail.com Backpatch-through: 19 --- src/backend/access/heap/pruneheap.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/src/backend/access/heap/pruneheap.c b/src/backend/access/heap/pruneheap.c index 29f4722b02d..54c69b69346 100644 --- a/src/backend/access/heap/pruneheap.c +++ b/src/backend/access/heap/pruneheap.c @@ -325,6 +325,14 @@ heap_page_prune_opt(Relation relation, Buffer buffer, Buffer *vmbuffer, bool record_free_space = false; Size freespace = 0; + /* + * Pin the VM page before taking the heap cleanup lock. This may + * occasionally lead to an unnecessary pin when the buffer is + * contended, but the same VM page covers many heap pages, so there is + * a good chance for the work to be reusable. + */ + visibilitymap_pin(relation, BufferGetBlockNumber(buffer), vmbuffer); + /* OK, try to get exclusive buffer lock */ if (!ConditionalLockBufferForCleanup(buffer)) return; @@ -340,9 +348,6 @@ heap_page_prune_opt(Relation relation, Buffer buffer, Buffer *vmbuffer, PruneFreezeResult presult; PruneFreezeParams params; - visibilitymap_pin(relation, BufferGetBlockNumber(buffer), - vmbuffer); - params.relation = relation; params.buffer = buffer; params.vmbuffer = *vmbuffer;