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

On Fri, Jan 29, 2021 at 1:24 PM Bharath Rupireddy
<bharath.rupireddyforpostgres@gmail.com> wrote:
>
> On Fri, Jan 29, 2021 at 1:17 PM Fujii Masao <masao.fujii@oss.nttdata.com> wrote:
> > >> But if the issue is only the inconsistency of test results,
> > >> we can go with the option (2)? Even with (2), we can make the test
> > >> stable by removing "valid" column and executing
> > >> postgres_fdw_get_connections() within the transaction?
> > >
> > > Hmmm, and we should have the tests at the start of the file
> > > postgres_fdw.sql before even we make any foreign server connections.
> >
> > We don't need to move the test if we always call postgres_fdw_disconnect_all() just before starting new transaction
andcalling postgres_fdw_get_connections() as follows?
 
> >
> > SELECT 1 FROM postgres_fdw_disconnect_all();
> > BEGIN;
> > ...
> > SELECT * FROM postgres_fdw_get_connections();
> > ...
>
> Yes, that works, but we cannot show true/false for the
> postgres_fdw_disconnect_all output.
>
> I will post the patch soon. Thanks a lot.

Attaching a patch that has following changes: 1) Now,
postgres_fdw_get_connections will only return set of active
connections server names not their valid state 2) The functions
postgres_fdw_get_connections, postgres_fdw_disconnect and
postgres_fdw_disconnect_all are now being tested within an explicit
xact block, this way the tests are more stable even with clobber cache
always builds.

I tested the patch here on my development system with
-DCLOBBER_CACHE_ALWAYS configuration, the tests look consistent.

Please review the patch.

With Regards,
Bharath Rupireddy.
EnterpriseDB: http://www.enterprisedb.com