Re: Set access strategy for parallel vacuum workers

On Wed, Apr 7, 2021 at 7:12 PM Bharath Rupireddy
<bharath(dot)rupireddyforpostgres(at)gmail(dot)com> wrote:
>
> On Wed, Apr 7, 2021 at 3:30 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> >
> > During recent developments in the vacuum, it has been noticed [1] that
> > parallel vacuum workers don't use any buffer access strategy. I think
> > we can fix it either by propagating the required information from the
> > leader or just get the access strategy in each worker separately. The
> > patches for both approaches for PG-13 are attached.
> >
> > Thoughts?
> >
> > [1] - https://www.postgresql.org/message-id/CAH2-Wz%3Dgf6FXW-jPVRdeCZk0QjhduCqH_XD3QbES9wPmhircuA%40mail.gmail.com
>
> Note: I have not followed the original discussion in [1].
>
> My understanding of the approach #1 i.e. propagating the vacuum
> strategy down to the parallel vacuum workers from the leader is that
> the same ring buffer (of 256KB for vacuum) will be used by both leader
> and all the workers.
>

No that is not the intention, each worker will use its ring buffer.
The first approach just passes the relevant information to workers so
that they can use the same strategy as used by the leader but both
will use separate ring buffer.

--
With Regards,
Amit Kapila.