Re: Emit fewer vacuum records by reaping removable tuples during pruning

On Fri, Jan 12, 2024 at 1:52 PM Melanie Plageman
<melanieplageman(at)gmail(dot)com> wrote:
> Yes, I was mixing the two together.
>
> I just want to make sure that we agree that, on master, when
> lazy_scan_prune() is called, the logic for whether or not to update
> the FSM after the first pass is:
>
> indexes == 0 || !has_lpdead_items || !index_vacuuming
>
> and when lazy_scan_noprune() is called, the logic for whether or not
> to update the FSM after the first pass is:
>
> indexes == 0 || !has_lpdead_items
>
> Those seem different to me.

This analysis seems correct to me, except that "when
lazy_scan_noprune() is called" should really say "when
lazy_scan_noprune() is called (and returns true)", because when it
returns false we fall through and call lazy_scan_prune() afterwards.

Here's a draft patch to clean up the inconsistency here. It also gets
rid of recordfreespace, because ISTM that recordfreespace is adding to
the confusion here rather than helping anything.

--
Robert Haas
EDB: http://www.enterprisedb.com