Subject: Re: Changed behavior in rewriteheap

From: Erik Nordström <[email-masked]>
Date: Fri, 22 Nov 2024 14:56:36 +0100

On Fri, Nov 22, 2024 at 2:26 PM Heikki Linnakangas <[email-masked]> wrote:

> On 22/11/2024 15:02, Matthias van de Meent wrote:
> > I think I'd go with a patch like attached, where the bulk writer
> > registers that it started with .relsize pages in the relfork, and use
> > that for smgrextend() decisions. It now also records pages_written as
> > a separate but accurate value.
>
> Looks good to me. Eric, can you confirm that Matthias's patch fixes the
> problem for you?
>
>
Yes, it solves the issue so it looks good.

Just a minor nit: the code uses both blokno as local variable for
pending_writes[i].blkno and directly accessing pending_writes[i].blkno.
Maybe it is better to just use the local variable. For example, change

++ b/src/backend/storage/smgr/bulk_write.c
@@ -304,7 +304,8 @@ smgr_bulk_flush(BulkWriteState *bulkstate)
                        }

                        smgrextend(bulkstate->smgr, bulkstate->forknum,
blkno, page, true);
-                       bulkstate->relsize = pending_writes[i].blkno + 1;
+                       bulkstate->relsize++;
+                       Assert(bulkstate->relsize == blkno + 1);

Just a suggestion.

Thanks for the quick action!

-Erik

---

From: Heikki Linnakangas <[email-masked]>
Date: Fri, 22 Nov 2024 16:53:00 +0200

> +                       Assert(bulkstate->relsize == blkno + 1);

Made that change and committed to master and REL_17_STABLE. I didn't 
bother with the assertion though. Also I removed the 'pages_written' 
field, it was not used for anything anymore.

Thanks!

-- 
Heikki Linnakangas
Neon (https://neon.tech)