Re: Parallel INSERT (INTO ... SELECT ...)

On Fri, Oct 16, 2020 at 3:43 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> On Thu, Oct 15, 2020 at 6:13 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> >
> > On Thu, Oct 15, 2020 at 9:56 AM Greg Nancarrow <gregn4422(at)gmail(dot)com> wrote:
> > >
> > > Also, I'm seeing a partition-related error when running
> > > installcheck-world - I'm investigating that.
> > >
> >
> > Okay.
> >
>
> The attached patch fixes this partition case for me. Basically, we
> need to check the parallel-safety of PartitionKey. I have only checked
> for partsupfunc but I think we need to check the parallel-safety of
> partexprs as well.

Thanks, I had already added the parallel-safety check for partexprs
when I saw this, so your patch hopefully completes all the
partition-related checks required.

> Also, I noticed that you have allowed for
> parallelism only when all expressions/functions involved with Insert
> are parallel-safe, can't we allow parallel-restricted case because
> anyway Inserts have to be performed by the leader for this patch.
>

Yes, I think you're right.
"A parallel restricted operation is one which cannot be performed in a
parallel worker, but which can be performed in the leader while
parallel query is in use."
I'll make the change and test that everything works OK.

Regards,
Greg Nancarrow
Fujitsu Australia