Re: non-HOT update not looking at FSM for large tuple update

On Tue, Mar 9, 2021 at 9:40 AM Floris Van Nee <florisvannee@optiver.com>
wrote:
>
> Hi,
>
> >
> > This patch fails to consider that len may be bigger than
MaxHeapTupleSize *
> > 0.98, which in this case triggers a reproducable
> > PANIC:
>
> Good catch! I've adapted the patch with your suggested fix.

Thank you both for testing and for the updated patch. It seems we should
add a regression test, but it's not clear which file it belongs in.
Possibly insert.sql?

> > One different question I have, though, is why we can't "just" teach
vacuum
> > to clean up trailing unused line pointers. As in, can't we trim the
line pointer
> > array when vacuum detects that the trailing line pointers on the page
are all
> > unused?

That seems like the proper fix, and I see you've started a thread for that.
I don't think that change in behavior would be backpatchable, but patch
here might have a chance at that.

--
John Naylor
EDB: http://www.enterprisedb.com