Re: WIP: Avoid creation of the free space map for small tables

On Thu, Jan 31, 2019 at 7:23 PM John Naylor <john(dot)naylor(at)2ndquadrant(dot)com> wrote:
>
> On Thu, Jan 31, 2019 at 1:52 PM John Naylor <john(dot)naylor(at)2ndquadrant(dot)com> wrote:
> >
> > On Thu, Jan 31, 2019 at 1:43 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> > > > I have an idea -- instead of adding a bunch of records and hoping that
> > > > the relation size and free space is consistent across platforms, how
> > > > about we revert to the original test input, and add a BRIN index? That
> > > > should have a FSM even with one record.
> > > >
> > >
> > > Why would BRIN index allow having FSM for heap relation?
> >
> > Oops, I forgot this file is for testing heaps only. That said, we
> > could possibly put most of the FSM tests such as
> >
> > SELECT * FROM fsm_page_contents(get_raw_page('test_rel_forks', 'fsm', 0));
> >
> > into brin.sql since we know a non-empty BRIN index will have a FSM.
>
> As in the attached. Applies on top of v20. First to revert to HEAD,
> second to move FSM tests to brin.sql. This is a much less invasive and
> more readable patch, in addition to being hopefully more portable.
>

I don't think that moving fsm tests to brin would be a good approach.
We want to have a separate test for each access method. I think if we
want to do something to avoid portability issues, maybe we can do what
Masahiko San has just suggested. OTOH, I think we are just good w.r.t
this issue with the last patch I sent. I think unless we see some
problem here, we should put energy into having a reproducible test for
the fourth problem mentioned in my mail up thread [1]. Do you think
it makes sense to run make check in loop for multiple times or do you
have any idea how we can have a reproducible test?

[1] - https://www.postgresql.org/message-id/CAA4eK1L%3DqWp_bJ5aTc9%2Bfy4Ewx2LPaLWY-RbR4a60g_rupCKnQ%40mail.gmail.com

--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com