Re: [PATCH] postgres_fdw connection caching - cause remote sessions linger till the local session exit

On Wed, Jul 1, 2020 at 2:45 PM Bharath Rupireddy <
bharath(dot)rupireddyforpostgres(at)gmail(dot)com> wrote:

> >
> > I've not looked at your patch deeply but if this problem is talking
> > only about postgres_fdw I think we should improve postgres_fdw, not
> > adding a GUC to the core. It’s not that all FDW plugins use connection
> > cache and postgres_fdw’s connection cache is implemented within
> > postgres_fdw, I think we should focus on improving postgres_fdw. I
> > also think it’s not a good design that the core manages connections to
> > remote servers connected via FDW. I wonder if we can add a
> > postgres_fdw option for this purpose, say keep_connection [on|off].
> > That way, we can set it per server so that remote connections to the
> > particular server don’t remain idle.
> >
>
> If I understand it correctly, your suggestion is to add
> keep_connection option and use that while defining the server object.
> IMO having keep_connection option at the server object level may not
> serve the purpose being discussed here.
> For instance, let's say I create a foreign server in session 1 with
> keep_connection on, and I want to use that
> server object in session 2 with keep_connection off and session 3 with
> keep_connection on and so on.
>

In my opinion, in such cases, one needs to create two server object one with
keep-connection ON and one with keep-connection off. And need to decide
to use appropriate for the particular session.

> One way we can change the server's keep_connection option is to alter
> the server object, but that's not a good choice,
> as we have to alter it at the system level.
>
> Overall, though we define the server object in a single session, it
> will be used in multiple sessions, having an
> option at the per-server level would not be a good idea.
>
> With Regards,
> Bharath Rupireddy.
> EnterpriseDB: http://www.enterprisedb.com
>
>
>

--
Rushabh Lathia