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

On Fri, Dec 11, 2020 at 3:46 PM Bharath Rupireddy
<bharath(dot)rupireddyforpostgres(at)gmail(dot)com> wrote:
> If we were to show invalidated connections in the output of
> postgres_fdw_get_connections(), we can ignore the entry and continue
> further if the user mapping sys cache search returns null tuple:
>
> umaptup = SearchSysCache1(USERMAPPINGOID, ObjectIdGetDatum(entry->key));
>
> if (!HeapTupleIsValid(umaptup))
> continue;

Any thoughts here?

> > > Also this makes me wonder if we should return both the server name and boolean flag indicating whether it's invalidated or not. If so, users can easily find the invalidated connection entry and disconnect it because there is no need to keep invalidated connection.
> > >
> >
> > Currently we are returning a list of foreing server names with whom
> > there exist active connections. If we somehow address the above
> > mentioned problem for invalid connections and choose to show them as
> > well, then how should our output look like? Is it something like we
> > prepare a list of pairs (servername, validflag)?
>
> If agreed on above point, we can output something like: (myserver1,
> valid), (myserver2, valid), (myserver3, invalid), (myserver4, valid)

And here on the output text?

In case we agreed on the above output format, one funniest thing could
occur is that if some hypothetical person has "valid" or "invalid" as
their foreign server names, they will have difficulty in reading their
output. (valid, valid), (valid, invalid), (invalid, valid), (invalid,
invalid).

Or should it be something like pairs of (server_name, true/false)?

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