Re: POC: Sharing record typmods between backends

On 2017-08-23 09:45:38 -0400, Robert Haas wrote:
> On Wed, Aug 23, 2017 at 1:46 AM, Andres Freund <andres(at)anarazel(dot)de> wrote:
> > For later commits in the series:
> > - Afaict the whole shared tupledesc stuff, as tqueue.c before, is
> > entirely untested. This baffles me. See also [1]. I can force the code
> > to be reached with force_parallel_mode=regress/1, but this absolutely
> > really totally needs to be reached by the default tests. Robert?
>
> force_parallel_mode=regress is a good way of testing this because it
> keeps the leader from doing the work, which would likely dodge any
> bugs that happened to exist. If you want to test something in the
> regular regression tests, using force_parallel_mode=on is probably a
> good way to do it.
>
> Also note that there are 3 buildfarm members that test with
> force_parallel_mode=regress on a regular basis, so it's not like there
> is no automated coverage of this area.

I don't think that's sufficient. make, and especially check-world,
should have a decent coverage of the code locally. Without having to
know about options like force_parallel_mode=regress. As e.g. evidenced
by the fact that Thomas's latest version crashed if you ran the tests
that way. If there's a few lines that aren't covered by the plain
tests, and more than a few node + parallelism combinations, I'm not
bothered much. But this is (soon hopefully was) a fairly complicated
piece of infrastructure - that should be exercised. If necessary that
can just be a BEGIN; SET LOCAL force_parallel_mode=on; query with
blessed descs;COMMIT or whatnot - it's not like we need something hugely
complicated here.

Greetings,

Andres Freund