Re: Questions/Observations related to Gist vacuum

On Mon, Oct 21, 2019 at 2:30 PM Andrey Borodin <x4mmm(at)yandex-team(dot)ru> wrote:
>
> Hi!
>
> > 18 окт. 2019 г., в 13:21, Dilip Kumar <dilipbalaut(at)gmail(dot)com> написал(а):
> >
> > On Fri, Oct 18, 2019 at 10:55 AM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> >>
> >>
> >> I think we can do it in general as adding some check for parallel
> >> vacuum there will look bit hackish.
> > I agree with that point.
> > It is not clear if we get enough
> >> benefit by keeping it for cleanup phase of the index as discussed in
> >> emails above. Heikki, others, let us know if you don't agree here.
> >
> > I have prepared a first version of the patch. Currently, I am
> > performing an empty page deletion for all the cases.
>
> I've took a look into the patch, and cannot understand one simple thing...
> We should not call gistvacuum_delete_empty_pages() for same gist_stats twice.
> Another way once the function is called we should somehow update or zero empty_leaf_set.
> Does this invariant hold in your patch?
>
Thanks for looking into the patch. With this patch now
GistBulkDeleteResult is local to single gistbulkdelete call or
gistvacuumcleanup. So now we are not sharing GistBulkDeleteResult,
across the calls so I am not sure how it will be called twice for the
same gist_stats? I might be missing something here?

--
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com