Re: Add two missing tests in 035_standby_logical_decoding.pl

On Sat, May 6, 2023 at 9:33 PM Drouvot, Bertrand
<bertranddrouvot(dot)pg(at)gmail(dot)com> wrote:
>
> On 5/6/23 3:28 PM, Amit Kapila wrote:
> > On Sat, May 6, 2023 at 1:52 PM Drouvot, Bertrand
> > <bertranddrouvot(dot)pg(at)gmail(dot)com> wrote:
>
> > Next steps:
> > =========
> > 1. The first thing is we should verify this theory by adding some LOG
> > in KeepLogSeg() to see if the _logSegNo is reduced due to the value
> > returned by XLogGetReplicationSlotMinimumLSN().
>
> Yeah, will do that early next week.
>
> > 2. The reason for the required file not being removed in the primary
> > is also that it has a physical slot which prevents the file removal.
>
> Yeah, agree. But this one is not an issue as we are not
> checking for the WAL file removal on the primary, do you agree?
>

Agreed.

> > 3. If the above theory is correct then I see a few possibilities to
> > fix this test (a) somehow ensure that restart_lsn of the physical slot
> > on standby is advanced up to the point where we can safely remove the
> > required files; (b) just create a separate test case by initializing a
> > fresh node for primary and standby where we only have logical slots on
> > standby. This will be a bit costly but probably less risky. (c) any
> > better ideas?
> >
>
> (c): Since, I think, the physical slot on the primary is not a concern for
> the reason mentioned above, then instead of (b):
>
> What about postponing the physical slot creation on the standby and the
> cascading standby node initialization after this test?
>

Yeah, that is also possible. But, I have a few questions regarding
that: (a) There doesn't seem to be a physical slot on cascading
standby, if I am missing something, can you please point me to the
relevant part of the test? (b) Which test is currently dependent on
the physical slot on standby?

--
With Regards,
Amit Kapila.