Re: Parallel copy - Mailing list pgsql-hackers

On Fri, Nov 13, 2020 at 2:25 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
>
> On Wed, Nov 11, 2020 at 10:42 PM vignesh C <vignesh21@gmail.com> wrote:
> >
> > On Tue, Nov 10, 2020 at 7:27 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
> > >
> > > On Tue, Nov 10, 2020 at 7:12 PM vignesh C <vignesh21@gmail.com> wrote:
> > > >
> > > > On Tue, Nov 3, 2020 at 2:28 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
> > > > >
> > > >
> > > > I have worked to provide a patch for the parallel safety checks. It
> > > > checks if parallely copy can be performed, Parallel copy cannot be
> > > > performed for the following a) If relation is temporary table b) If
> > > > relation is foreign table c) If relation has non parallel safe index
> > > > expressions d) If relation has triggers present whose type is of non
> > > > before statement trigger type e) If relation has check constraint
> > > > which are not parallel safe f) If relation has partition and any
> > > > partition has the above type. This patch has the checks for it. This
> > > > patch will be used by parallel copy implementation.
> > > >
> > >
> > > How did you ensure that this is sufficient? For parallel-insert's
> > > patch we have enabled parallel-mode for Inserts and ran the tests with
> > > force_parallel_mode to see if we are not missing anything. Also, it
> > > seems there are many common things here w.r.t parallel-insert patch,
> > > is it possible to prepare this atop that patch or do you have any
> > > reason to keep this separate?
> > >
> >
> > I have done similar testing for copy too, I had set force_parallel
> > mode to regress, hardcoded in the code to pick parallel workers for
> > copy operation and ran make installcheck-world to verify. Many checks
> > in this patch are common between both patches, but I was not sure how
> > to handle it as both the projects are in-progress and are being
> > updated based on the reviewer's opinion. How to handle this?
> > Thoughts?
> >
>
> I have not studied the differences in detail but if it is possible to
> prepare it on top of that patch then there shouldn't be a problem. To
> avoid confusion if you want you can always either post the latest
> version of that patch with your patch or point to it.
>

I have made this as a separate patch as of now. I will work on to see
if I can use Greg's changes as it is or if required I will provide a
few review comments on top of Greg's patch so that it is usable for
parallel copy too and later post a separate patch with the changes on
top of it. I will retain it as a separate patch till that time.

Regards,
Vignesh
EnterpriseDB: http://www.enterprisedb.com