Re: Parallel Inserts in CREATE TABLE AS

On Wed, Dec 16, 2020 at 12:06 PM Bharath Rupireddy
<bharath(dot)rupireddyforpostgres(at)gmail(dot)com> wrote:
>
> On Tue, Dec 15, 2020 at 5:53 PM Bharath Rupireddy
> <bharath(dot)rupireddyforpostgres(at)gmail(dot)com> wrote:
> > I'm merging them to the original patch set and adding the test cases
> > to cover these cases. I will post the updated patch set soon.
>
> Attaching v12 patch set.
>
> 0001 - parallel inserts without tuple cost enforcement.
> 0002 - enforce planner for parallel tuple cost
> 0003 - test cases
>
> Please review it further.
>

I think it will be clean to implement the parallel CTAS when a
top-level node is the gather node. Basically, the idea is that
whenever we get the gather on the top which doesn't have any
projection then we can push down the dest receiver directly to the
worker. I agree that append is an exception that doesn't do any extra
processing other than appending the results, So IMHO it would be
better that in the first part we parallelize the plan where gather
node on top. I see that we have already worked on the patch where the
append node is on top so I would suggest that we can keep that part in
a separate patch.

--
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com