Re: utility commands benefiting from parallel plan

On Wed, Sep 13, 2017 at 2:29 PM, Haribabu Kommi
<kommi(dot)haribabu(at)gmail(dot)com> wrote:
>
>
> On Wed, Sep 13, 2017 at 4:17 PM, Rafia Sabih <rafia(dot)sabih(at)enterprisedb(dot)com>
> wrote:
>>
>> On Fri, Sep 1, 2017 at 12:31 PM, Haribabu Kommi
>> <kommi(dot)haribabu(at)gmail(dot)com> wrote:
>> >
>> > Hi All,
>> >
>> > Attached a rebased patch that supports parallelism for the queries
>> > that are underneath of some utility commands such as CREATE TABLE AS
>> > and CREATE MATERIALIZED VIEW.
>> >
>> > Note: This patch doesn't make the utility statement (insert operation)
>> > to run in parallel. It only allows the select query to be parallel if
>> > the
>> > query
>> > is eligible for parallel.
>> >
>>
>> Here is my feedback fro this patch,
>>
>> - The patch is working as expected, all regression tests are passing
>
>
> Thanks for the review.
>
>>
>> - I agree with Dilip that having similar mechanism for 'insert into
>> select...' statements would add more value to the patch, but even then
>> this looks like a good idea to extend parallelism for atleast a few of
>> the write operations
>
>
> Yes, I also agree that supporting of 'insert into select' will provide more
> benefit. I already tried to support the same in [1], but it have many
> drawbacks especially with triggers. To support a proper parallel support
> for DML queries, I feel the logic of ParalleMode needs an update to
> avoid the errors from PreventCommandIfParallelMode() function to
> identify whether it is nested query operation and that should execute
> only in backend and etc.
>
> As the current patch falls into DDL category that gets benefited from
> parallel query, because of this reason, I didn't add the 'insert into
> select'
> support into this patch. Without support of it also, it provides the
> benefit.
> I work on supporting the DML write support with parallel query as a
> separate patch.
>
Sounds sensible. In that case, I'll be marking this patch ready for committer.
>
> [1] -
> https://www.postgresql.org/message-id/CAJrrPGfo58TrYxnqwnFAo4%2BtYr8wUH-oC0dJ7V9x7gAOZeaz%2BQ%40mail.gmail.com
>
>

--
Regards,
Rafia Sabih
EnterpriseDB: http://www.enterprisedb.com/