Re: Asynchronous Append on postgres_fdw nodes.

On Wed, Feb 10, 2021 at 9:31 PM Etsuro Fujita <etsuro(dot)fujita(at)gmail(dot)com> wrote:
> Please find attached an updated patch.

I noticed that this doesn’t work for cases where ForeignScans are
executed inside functions, and I don’t have any simple solution for
that. So I’m getting back to what Horiguchi-san proposed for
postgres_fdw to handle concurrent fetches from a remote server
performed by multiple ForeignScan nodes that use the same connection.
As discussed before, we would need to create a scheduler for
performing such fetches in a more optimized way to avoid a performance
degradation in some cases, but that wouldn’t be easy. Instead, how
about reducing concurrency as an alternative? In his proposal,
postgres_fdw was modified to perform prefetching pretty aggressively,
so I mean removing aggressive prefetching. I think we could add it to
postgres_fdw later maybe as the server/table options. Sorry for the
back and forth.

Best regards,
Etsuro Fujita