Re: Nonrandom scanned_pages distorts pg_class.reltuples set by VACUUM

Hi,

On 2022-02-16 19:43:09 -0800, Peter Geoghegan wrote:
> It makes the code in vacuumlazy.c much cleaner. In fact, that's how commit
> 44fa8488 started off -- purely as refactoring work.

The problem is that it didn't end up as that. You combined refactoring with
substantial changes. And described it large and generic terms.

> > You didn't really give a heads up that you're about to commit either. There's
> > a note at the bottom of [1], a very long email, talking about committing in a
> > couple of weeks. After which there was substantial discussion of the patchset.
>
> How can you be surprised that I committed 44fa8488? It's essentially
> the same patch as the first version, posted November 22 -- almost 3
> months ago.

It's a contentious thread. I asked for things to be split. In that context,
it's imo common curtesy for non-trivial patches to write something like

While the rest of the patchset is contentious, I think 0001 is ready to
go. I'd like to commit it tomorrow, unless somebody protests.

> And it's certainly not a big patch (though it is complicated).

For me a vacuum change with the following diffstat is large:
3 files changed, 515 insertions(+), 297 deletions(-)

> > It doesn't look to me like there was a lot of review for 44fa8488, despite it
> > touching very critical parts of the code. I'm listed as a reviewer, that was a
> > few months ago, and rereading my review I don't think it can be read to agree
> > with the state of the code back then.
>
> Can you be more specific?

Most importantly:

On 2021-11-22 11:29:56 -0800, Andres Freund wrote:
> I think this is a change mostly in the right direction. But as formulated this
> commit does *WAY* too much at once.

I do not know how to state more clearly that I think this is not a patch in a
committable shape.

but also:

On 2021-11-22 11:29:56 -0800, Andres Freund wrote:
> I think it should be doable to add an isolation test for this path. There have
> been quite a few bugs around the wider topic...

Greetings,

Andres Freund