Re: Parallel execution and prepared statements

On Thu, Dec 1, 2016 at 7:57 AM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> 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.

OK, then my vote is to do it that way for now.

--
Robert Haas
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