Date: Fri, 15 Mar 2024 16:45:18 +0000
From: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>,
	Nathan Bossart <nathandbossart@gmail.com>,
	PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: Introduce XID age and inactive timeout based replication slot
 invalidation
Message-ID: <ZfR7HuzFEswakt/a@ip-10-97-1-34.eu-west-3.compute.internal>
References: <20240301221108.GB3024365@nathanxps13>
 <CALj2ACUprrvq=R9WBnCEtguBhSp0X+krTCGDvkHyBdawyex-kA@mail.gmail.com>
 <20240303214434.GA3036597@nathanxps13>
 <CAA4eK1+NUeb21bYa9K5mVsFHcw-xodGLkN9QoqJXym7sD3LtZA@mail.gmail.com>
 <CALj2ACVr8ra-yp8CwiBq=Pc9Kkq64z=zDvoFxMK3K4wSDhKMmg@mail.gmail.com>
 <CAA4eK1KxsMg4bnxRZ0U3dZ3irFoR2=TfUCOFig3ccHoRPp5iWg@mail.gmail.com>
 <CALj2ACU-sJdiLfAcWd+8hnt4HSojH0UWFGnaGr9gxb2bYzYYSA@mail.gmail.com>
 <CAA4eK1++=fOpmsQKugQQRtQr2wmiintjKEhpuOch9=phxirAfg@mail.gmail.com>
 <CALj2ACVd_dizYQiZwwUfsb+hG-fhGYo_kEDq0wn_vNwQvOrZHg@mail.gmail.com>
 <CAA4eK1+02XhKht3EB=RgzQ=2zyb9Sv4=9iC=yt1j4FfVy0-5kg@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <CAA4eK1+02XhKht3EB=RgzQ=2zyb9Sv4=9iC=yt1j4FfVy0-5kg@mail.gmail.com>
Archived-At: <https://www.postgresql.org/message-id/ZfR7HuzFEswakt/a%40ip-10-97-1-34.eu-west-3.compute.internal>
Precedence: bulk

Hi,

On Thu, Mar 14, 2024 at 12:24:00PM +0530, Amit Kapila wrote:
> On Wed, Mar 13, 2024 at 9:24 PM Bharath Rupireddy
> <bharath.rupireddyforpostgres@gmail.com> wrote:
> >
> > On Wed, Mar 13, 2024 at 9:21 AM Amit Kapila <amit.kapila16@gmail.com> wrote:
> > >
> > > > So, how about we turn conflict_reason to only report the reasons that
> > > > actually cause conflict with recovery for logical slots, something
> > > > like below, and then have invalidation_cause as a generic column for
> > > > all sorts of invalidation reasons for both logical and physical slots?
> > >
> > > If our above understanding is correct then coflict_reason will be a
> > > subset of invalidation_reason. If so, whatever way we arrange this
> > > information, there will be some sort of duplicity unless we just have
> > > one column 'invalidation_reason' and update the docs to interpret it
> > > correctly for conflicts.
> >
> > Yes, there will be some sort of duplicity if we emit conflict_reason
> > as a text field. However, I still think the better way is to turn
> > conflict_reason text to conflict boolean and set it to true only on
> > rows_removed and wal_level_insufficient invalidations. When conflict
> > boolean is true, one (including all the tests that we've added
> > recently) can look for invalidation_reason text field for the reason.
> > This sounds reasonable to me as opposed to we just mentioning in the
> > docs that "if invalidation_reason is rows_removed or
> > wal_level_insufficient it's the reason for conflict with recovery".
> >
> 
> Fair point. I think we can go either way. Bertrand, Nathan, and
> others, do you have an opinion on this matter?

Sounds like a good approach to me and one will be able to quickly identify
if a conflict occured.

Regards,

-- 
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com