Re: Parallel INSERT (INTO ... SELECT ...)

> >
> > I think you still need to work on the costing part, basically if we
> > are parallelizing whole insert then plan is like below
> >
> > -> Gather
> > -> Parallel Insert
> > -> Parallel Seq Scan
> >
> > That means the tuple we are selecting via scan are not sent back to
> > the gather node, so in cost_gather we need to see if it is for the
> > INSERT then there is no row transferred through the parallel queue
> > that mean we need not to pay any parallel tuple cost.
>
> I just looked into the parallel CTAS[1] patch for the same thing, and
> I can see in that patch it is being handled.
>
> [1] https://www.postgresql.org/message-id/CALj2ACWFq6Z4_jd9RPByURB8-Y8wccQWzLf%2B0-Jg%2BKYT7ZO-Ug%40mail.gmail.com
>

Hi Dilip,

You're right, the costing for Parallel Insert is not done and
finished, I'm still working on the costing, and haven't posted an
updated patch for it yet.
As far as cost_gather() method is concerned, for Parallel INSERT, it
can probably use the same costing approach as the CTAS patch except in
the case of a specified RETURNING clause.

Regards,
Greg Nancarrow
Fujitsu Australia