Re: Transactions involving multiple postgres foreign servers, take 2

At Tue, 20 Oct 2020 15:53:29 +0900, Masahiko Sawada <masahiko(dot)sawada(at)2ndquadrant(dot)com> wrote in
> On Tue, 20 Oct 2020 at 13:23, tsunakawa(dot)takay(at)fujitsu(dot)com
> <tsunakawa(dot)takay(at)fujitsu(dot)com> wrote:
> >
> > From: Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)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 cancellation in 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.
> >
>
> I think it doesn't matter whether in FDW framework or not. The user
> normally doesn't care which backend processes connecting to foreign
> servers. They will attempt to cancel the query like always if they
> realized that a backend gets stuck. There are surely plenty of users
> who use query cancellation.

The most serious impact from inability of canceling a query on a
certain session is that server-restart is required to end such a
session.

regards.

--
Kyotaro Horiguchi
NTT Open Source Software Center