Re: New vacuum option to do only freezing

On Sat, Jan 12, 2019 at 3:27 AM Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>
> On Fri, Jan 11, 2019 at 1:14 AM Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
> > Attached the updated patch. Please review it.
>
> I'm quite confused by this patch. It seems to me that the easiest way
> to implement this patch would be to (1) make lazy_space_alloc take the
> maxtuples = MaxHeapTuplesPerPage branch when the new option is
> specified, and then (2) forget about them after each page i.e.
>
> if (nindexes == 0 &&
> vacrelstats->num_dead_tuples > 0)
> {
> ...
> }
> else if (skipping index cleanup)
> vacrelstats->num_dead_tuples = 0;
>
> I don't see why it should touch the logic inside lazy_vacuum_page() or
> the decision about whether to truncate.
>

I think that because the tuples that got dead after heap_page_prune()
looked are recorded but not removed without lazy_vacuum_page() we need
to process them in lazy_vacuum_page(). For decision about whether to
truncate we should not change it, so I will fix it. It should be an
another option to control whether to truncate if we want.

Regards,

--
Masahiko Sawada
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center