Re: [HACKERS] Block level parallel vacuum

On Tue, Oct 15, 2019 at 6:33 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> On Tue, Oct 15, 2019 at 1:26 PM Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
> >
> > On Tue, Oct 15, 2019 at 4:15 PM Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
> > >
> > > > > > If we avoid postponing deleting empty pages till the cleanup phase,
> > > > > > then we don't have the problem for gist indexes.
> > > > >
> > > > > Yes. But considering your pointing out I guess that there might be
> > > > > other index AMs use the stats returned from bulkdelete in the similar
> > > > > way to gist index (i.e. using more larger structure of which
> > > > > IndexBulkDeleteResult is just the first field). If we have the same
> > > > > concern the parallel vacuum still needs to deal with that as you
> > > > > mentioned.
> > > > >
> > > >
> > > > Right, apart from some functions for memory allocation/estimation and
> > > > stats copy, we might need something like amcanparallelvacuum, so that
> > > > index methods can have the option to not participate in parallel
> > > > vacuum due to reasons similar to gist or something else. I think we
> > > > can work towards this direction as this anyway seems to be required
> > > > and till we reach any conclusion for gist indexes, you can mark
> > > > amcanparallelvacuum for gist indexes as false.
> > >
> > > Agreed. I'll create a separate patch to add this callback and change
> > > parallel vacuum patch so that it checks the participation of indexes
> > > and then vacuums on un-participated indexes after parallel vacuum.
> >
> > amcanparallelvacuum is not necessary to be a callback, it can be a
> > boolean field of IndexAmRoutine.
> >
>
> Yes, it will be a boolean. Note that for parallel-index scans, we
> already have amcanparallel.
>

Attached updated patch set. 0001 patch introduces new index AM field
amcanparallelvacuum. All index AMs except for gist sets true for now.
0002 patch incorporated the all comments I got so far.

Regards,

--
Masahiko Sawada