Re: [HACKERS] utility commands benefiting from parallel plan

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От Haribabu Kommi
Тема Re: [HACKERS] utility commands benefiting from parallel plan
Дата
Msg-id CAJrrPGdn+UYSfRH2iQ4_AyN4oV7cVzmczdtCeQQ4zAO5kXT4sQ@mail.gmail.com
обсуждение исходный текст
Ответ на Re: [HACKERS] utility commands benefiting from parallel plan  (Rafia Sabih <rafia.sabih@enterprisedb.com>)
Ответы Re: [HACKERS] utility commands benefiting from parallel plan  (Rafia Sabih <rafia.sabih@enterprisedb.com>)
Список pgsql-hackers
Дерево обсуждения


On Wed, Sep 13, 2017 at 4:17 PM, Rafia Sabih <rafia.sabih@enterprisedb.com> wrote:
On Fri, Sep 1, 2017 at 12:31 PM, Haribabu Kommi
<kommi.haribabu@gmail.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.




Regards,
Hari Babu
Fujitsu Australia

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