On 6/5/21 22:12, Stephen Frost wrote:
* Etsuro Fujita (etsuro.fuj...@gmail.com) wrote:
I think the user should be careful about this. How about adding a
note about it to the “Asynchronous Execution Options” section in
postgres-fdw.sgml, like the attached?
+1
... then again, it'd really be better if we could figure out a way to
just do the right thing here. I haven't looked at this in depth but I
would think that the overhead of async would be well worth it just about
any time there's more than one foreign server involved. Is it not
reasonable to have a heuristic where we disable async in the cases where
there's only one foreign server, but have it enabled all the other time?
While continuing to allow users to manage it explicitly if they want.
Bechmarking of SELECT from foreign partitions hosted on the same server,
i see results:
With async append:
1 partition - 178 ms; 4 - 263; 8 - 450; 16 - 860; 32 - 1740.
Without:
1 - 178 ms; 4 - 583; 8 - 1140; 16 - 2302; 32 - 4620.
So, these results show that we have a reason to use async append in the
case where there's only one foreign server.
--
regards,
Andrey Lepikhov
Postgres Professional
