Re: Parallel execution and prepared statements

On Wed, Nov 30, 2016 at 11:57 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Tue, Nov 29, 2016 at 6:24 AM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>>
>> Robert, do you have any better ideas for this problem?
>
> Not really. I think your prepared_stmt_parallel_query_v2.patch is
> probably the best approach proposed so far, but I wonder why we need
> to include DestCopyOut and DestTupleStore. DestIntoRel and
> DestTransientRel both write to an actual relation, which is a problem
> for parallel mode, but I think the others don't.
>

I have tried to restrict all the non-readonly operation modes or modes
where parallelism might not make sense like DestTupleStore. If we
want to just prohibit the cases where it can fail now, then I think
prohibiting only DestIntoRel should be sufficient because that is a
case where the user is allowed to do DDL for an already prepared read
only statement like Create Table AS .. EXECUTE.

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