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

On Thu, Nov 29, 2018 at 3:07 PM John Naylor <jcnaylor(at)gmail(dot)com> wrote:
> > Few more comments:
> > -------------------------------
> > 1. I think we can add some test(s) to test the new functionality, may
> > be something on the lines of what Robert has originally provided as an
> > example of this behavior [1].
>
> Done. I tried adding it to several schedules, but for some reason
> vacuuming an empty table failed to truncate the heap to 0 blocks.
> Putting the test in its own group fixed the problem, but that doesn't
> seem ideal.
>

It might be because it fails the should_attempt_truncation() check.
See below code:

if (should_attempt_truncation(vacrelstats))
lazy_truncate_heap(onerel, vacrelstats, vac_strategy);

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