On 22.09.2020 15:52, Konstantin Knizhnik wrote:


On 20.08.2020 10:36, Kyotaro Horiguchi wrote:
At Wed, 19 Aug 2020 23:25:36 -0500, Justin Pryzby <pry...@telsasoft.com> wrote in
On Thu, Jul 02, 2020 at 11:14:48AM +0900, Kyotaro Horiguchi wrote:
As the result of a discussion with Fujita-san off-list, I'm going to
hold off development until he decides whether mine or Thomas' is
better.
The latest patch doesn't apply so I set as WoA.
https://commitfest.postgresql.org/29/2491/
Thanks. This is rebased version.

At Fri, 14 Aug 2020 13:29:16 +1200, Thomas Munro <thomas.mu...@gmail.com> wrote in
Either way, we definitely need patch 0001.  One comment:

-CreateWaitEventSet(MemoryContext context, int nevents)
+CreateWaitEventSet(MemoryContext context, ResourceOwner res, int nevents)

I wonder if it's better to have it receive ResourceOwner like that, or
to have it capture CurrentResourceOwner.  I think the latter is more
common in existing code.
There's no existing WaitEventSets belonging to a resowner. So
unconditionally capturing CurrentResourceOwner doesn't work well. I
could pass a bool instead but that make things more complex.

Come to think of "complex", ExecAsync stuff in this patch might be
too-much for a short-term solution until executor overhaul, if it
comes shortly. (the patch of mine here as a whole is like that,
though..). The queueing stuff in postgres_fdw is, too.

regards.



Hi,
Looks like current implementation of asynchronous append incorrectly handle LIMIT clause:

psql:append.sql:10: ERROR:  another command is already in progress
CONTEXT:  remote SQL command: CLOSE c1



Just FYI: the following patch fixes the problem:

--- a/contrib/postgres_fdw/postgres_fdw.c
+++ b/contrib/postgres_fdw/postgres_fdw.c
@@ -1667,6 +1667,11 @@ remove_async_node(ForeignScanState *node)

         if (cur == node)
         {
+            PGconn *conn = curstate->s.conn;
+
+            while(PQisBusy(conn))
+                PQclear(PQgetResult(conn));
+
             prev_state->waiter = curstate->waiter;

             /* relink to the previous node if the last node was removed */

--
Konstantin Knizhnik
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company

diff --git a/contrib/postgres_fdw/postgres_fdw.c b/contrib/postgres_fdw/postgres_fdw.c
index 1482436..9fe16cf 100644
--- a/contrib/postgres_fdw/postgres_fdw.c
+++ b/contrib/postgres_fdw/postgres_fdw.c
@@ -1667,6 +1667,11 @@ remove_async_node(ForeignScanState *node)
 
 		if (cur == node)
 		{
+			PGconn *conn = curstate->s.conn;
+
+			while(PQisBusy(conn))
+				PQclear(PQgetResult(conn));
+
 			prev_state->waiter = curstate->waiter;
 
 			/* relink to the previous node if the last node was removed */

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