RE: Transactions involving multiple postgres foreign servers, take 2

From: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
> I don't think the inability to cancel all session at once cannot be a
> reason not to not to allow operators to cancel a stuck session.

Yeah, I didn't mean to discount the ability to cancel queries.  I just want to confirm how the user can use the
cancellationin practice.  I didn't see how the user can use the cancellation in the FDW framework, so I asked about it.
We have to think about the user's context if we regard canceling commits as important. 


> > Furthermore, FDW is not cancellable in general.  So, I don't see a point in
> trying hard to make only commit be cancelable.
>
> I think that it is quite important that operators can cancel any
> process that has been stuck for a long time. Furthermore, postgres_fdw
> is more likely to be stuck since network is involved so the usefulness
> of that feature would be higher.

But lower than practical performance during normal operation.

BTW, speaking of network, how can postgres_fdw respond quickly to cancel request when libpq is waiting for a reply from
adown foreign server?  Can the user continue to use that session after cancellation? 


Regards
Takayuki Tsunakawa