Re: Option to not use ringbuffer in VACUUM, using it in failsafe mode

Hi,

On 2023-01-11 11:06:26 -0800, Peter Geoghegan wrote:
> On Wed, Jan 11, 2023 at 10:58 AM Andres Freund <andres(at)anarazel(dot)de> wrote:
> > Any idea about the name? The obvious thing is to reference ring buffers in the
> > option name, but that's more of an implementation detail...
>
> What are the chances that anybody using this feature via a manual
> VACUUM command will also use INDEX_CLEANUP off? It's not really
> supposed to be used routinely, at all. Right? It's just for
> emergencies.

I think it's also quite useful for e.g. vacuuming after initial data loads or
if you need to do a first vacuum after a lot of bloat accumulated due to a
stuck transaction.

> Perhaps it can be tied to INDEX_CLEANUP=off? That makes it hard to get
> just the behavior you want when testing VACUUM, but maybe that doesn't
> matter.

I don't like that - it's also quite useful to disable use of ringbuffers when
you actually need to clean up indexes. Especially when we have a lot of dead
tuples we'll rescan indexes over and over...

Greetings,

Andres Freund