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

On Tue, Sep 22, 2020 at 10:26 AM Greg Nancarrow <gregn4422(at)gmail(dot)com> wrote:
>
> For cases where it can't be allowed (e.g. INSERT into a table with
> foreign keys, or INSERT INTO ... SELECT ... ON CONFLICT ... DO UPDATE
> ...") it at least allows parallelism of the SELECT part.
>

Thanks Greg for the patch.

I have few points (inspired from parallel copy feature work) to mention:

1. What if the target table is a foreign table or partitioned table?
2. What happens if the target table has triggers(before statement,
after statement, before row, after row) that are parallel unsafe?
3. Will each worker be doing single row insertions or multi inserts?
If single row insertions, will the buffer lock contentions be more?
5. How does it behave with toast columns values?
6. How does it behave if we have a RETURNING clause with INSERT INTO SELECT?

I'm looking forward to seeing some initial numbers on execution times
with and without patch.

With Regards,
Bharath Rupireddy.
EnterpriseDB: http://www.enterprisedb.com