Re: Asynchronous Append on postgres_fdw nodes.

"On Thu, Nov 26, 2020 at 9:28 AM movead.li@highgo.ca
<movead.li@highgo.ca> wrote:
>
>
> I test the patch and occur several issues as blow:
>
> Issue one:
> Get a Assert error at 'Assert(bms_is_member(i, node->as_needrequest));' in
> ExecAppendAsyncRequest() function when I use more than two foreign table
> on different foreign server.
>
> I research the code and do such change then the Assert problem disappear.
>
> @@ -1004,6 +1004,7 @@ ExecAppendAsyncResponse(AsyncRequest *areq) bms_del_member(node->as_needrequest,
areq->request_index);node->as_asyncpending = bms_add_member(node->as_asyncpending, areq->request_index); +
node->as_lastasyncplan= INVALID_SUBPLAN_INDEX; return false; } 
>
> Issue two:
> Then I test and find if I have sync subplan and async sunbplan, it will run over
> the sync subplan then the async turn, I do not know if it is intent.

I only just noticed this patch. It's very interesting to me given the
ongoing work happening on postgres_fdw batching and the way libpq
pipelining is looking like it's getting there. I'll study up on the
executor and see if I can understand this well enough to hack together
a PoC to make it use libpq batching.

Have you taken a look at how this patch may overlap with those?

See -hackers threads:

* "POC: postgres_fdw insert batching" [1]
* "PATCH: Batch/pipelining support for libpq" [2]

[1]
https://www.postgresql.org/message-id/OSBPR01MB2982039EA967F0304CC6A3ECFE0B0@OSBPR01MB2982.jpnprd01.prod.outlook.com
[2] https://www.postgresql.org/message-id/20201026190936.GA18705@alvherre.pgsql