Re: Do we need to handle orphaned prepared transactions in the server?

Thank you everyone for the detailed feedback.

On Fri, Apr 17, 2020 at 5:40 AM Michael Paquier <michael(at)paquier(dot)xyz> wrote:

> On Thu, Apr 16, 2020 at 03:11:51PM -0400, Tom Lane wrote:
> > Even if I liked the core idea, loading the functionality onto VACUUM
> seems
> > like a fairly horrid design choice. It's quite unrelated to what that
> > command does. In the autovac code path, it's going to lead to multiple
> > autovac workers all complaining simultaneously about the same problem.
> > But having manual vacuums complain about issues unrelated to the task at
> > hand is also a seriously poor bit of UX design. Moreover, that won't do
> > all that much to surface problems, since most(?) installations never run
> > manual vacuums; or if they do, the "manual" runs are really done by a
> cron
> > job or the like, which is not going to notice the warnings. So you still
> > need a log-scraping tool.
>
> +1.
>
> > If we were going to go down the path of periodically logging warnings
> > about old prepared transactions, some single-instance background task
> > like the checkpointer would be a better place to do the work in. But
> > I'm not really recommending that, because I agree with Robert that
> > we just plain don't want this functionality.
>
> I am not sure that the checkpointer is a good place to do that either,
> joining back with your argument in the first paragraph of this email
> related to vacuum. One potential approach would be a contrib module
> that works as a background worker? However, I would think that
> finding a minimum set of requirements that we think are generic enough
> for most users would be something hard to draft a list of. If we had
> a small, minimal contrib/ module in core that people could easily
> extend for their own needs and that we would intentionally keep as
> minimal, in the same spirit as say passwordcheck, perhaps..
> --
> Michael
>

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