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

Hi,

On 2023-01-11 16:18:34 -0500, Tom Lane wrote:
> Peter Geoghegan <pg@bowt.ie> writes:
> > On Wed, Jan 11, 2023 at 11:18 AM Andres Freund <andres@anarazel.de> wrote:
> >> 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...
>
> > That's a fair point.
>
> > My vote goes to "REUSE_BUFFERS", then.
>
> I wonder whether it could make sense to allow a larger ringbuffer size,
> rather than just the limit cases of "on" and "off".

I can see that making sense, particularly if we were to later extend this to
other users of ringbuffers. E.g. COPYs us of the ringbuffer makes loading of
data > 16MB but also << s_b vastly slower, but it can still be very important
to use if there's lots of parallel processes loading data.