Re: asynchronous execution

On Fri, Feb 3, 2017 at 5:04 AM, Antonin Houska <ah(at)cybertec(dot)at> wrote:

> Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp> wrote:
>
> > I noticed that this patch is conflicting with 665d1fa (Logical
> > replication) so I rebased this. Only executor/Makefile
> > conflicted.
>
> I was lucky enough to see an infinite loop when using this patch, which I
> fixed by this change:
>
> diff --git a/src/backend/executor/execAsync.c
> b/src/backend/executor/execAsync.c
> new file mode 100644
> index 588ba18..9b87fbd
> *** a/src/backend/executor/execAsync.c
> --- b/src/backend/executor/execAsync.c
> *************** ExecAsyncEventWait(EState *estate, long
> *** 364,369 ****
> --- 364,370 ----
>
> if ((w->events & WL_LATCH_SET) != 0)
> {
> + ResetLatch(MyLatch);
> process_latch_set = true;
> continue;
> }

Hi, I've been testing this patch because seemed like it would help a use
case of mine, but can't tell if it's currently working for cases other than
a local parent table that has many child partitions which happen to be
foreign tables. Is it? I was hoping to use it for a case like:

select x, sum(y) from one_remote_table
union all
select x, sum(y) from another_remote_table
union all
select x, sum(y) from a_third_remote_table

but while aggregates do appear to be pushed down, it seems that the remote
tables are being queried in sequence. Am I doing something wrong?