Re: Create Action for psql when NOTIFY Recieved

> On Sep 4, 2017, at 10:25 PM, Nico Williams <nico(at)cryptonector(dot)com> wrote:
>
> On Mon, Sep 4, 2017 at 4:21 PM Steve Atkins <steve(at)blighty(dot)com> wrote:
> >
>
> Me too.
>
> https://github.com/wttw/pgsidekick
>
> Select-based, sends periodic keep-alives to keep the connection open, outputs payloads in a way that's friendly to pipe into xargs. (Also the bare bones of a notify-based scheduler).
>
> Without any kind of access controls on NOTIFY channels, nor any kind of payload validation, i just don't feel comfortable using the payload at all. Besides, the payload is hardly necessary given that there's a database on which you can scribble the payload :) It suffices that you receive a notification, and you can then check if there's anything to do.
>
> My version of this doesn't have connection keepalives, but that's ok because that can be added in the form of.... notifications, and the consumer of pqasyncnotifier can implement timeouts. But i agree that timeouts and keepalives would be nice, and even invoking a given SQL function would be nice.
>
> But the question i have is: how to get such functionality integrated into PostgreSQL? Is a standalone program (plus manpage plus Makefile changes) enough, or would a psql \wait command be better?

There's not really any need to integrate it into postgresql at all. It doesn't rely on any details of the core implementation - it's just a normal SQL client, a pretty trivial one.

(Whether psql could usefully be reworked to listen for activity on the connection when it's not actively executing a query is another question).

Cheers,
Steve