Re: utility commands benefiting from parallel plan

On Thu, Sep 14, 2017 at 2:42 PM, Rafia Sabih <rafia(dot)sabih(at)enterprisedb(dot)com>
wrote:

> 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.

Thanks for the review.

Regards,
Hari Babu
Fujitsu Australia