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From: Bertrand Drouvot <[email protected]>
To: Bharath Rupireddy <[email protected]>
Cc: Masahiko Sawada <[email protected]>
Cc: Amit Kapila <[email protected]>
Cc: shveta malik <[email protected]>
Cc: Nathan Bossart <[email protected]>
Cc: PostgreSQL Hackers <[email protected]>
Subject: Re: Introduce XID age and inactive timeout based replication slot invalidation
Date: Tue, 2 Apr 2024 08:33:40 +0000
Message-ID: <ZgvC5CocS/[email protected]> (raw)
In-Reply-To: <CALj2ACVNLjnzcRz2Wpx2owgWkJ52jnOgPxUzUwzi7Wh4-36P7g@mail.gmail.com>
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Hi,

On Tue, Apr 02, 2024 at 12:41:35PM +0530, Bharath Rupireddy wrote:
> On Tue, Apr 2, 2024 at 11:58 AM Bertrand Drouvot
> <[email protected]> wrote:
> >
> > > Or a simple solution is that the slotsync worker updates
> > > inactive_since as it does for non-synced slots, and disables
> > > timeout-based slot invalidation for synced slots.
> >
> > Yeah, I think the main question to help us decide is: do we want to invalidate
> > "inactive" synced slots locally (in addition to synchronizing the invalidation
> > from the primary)?
> 
> I think this approach looks way simpler than the other one. The other
> approach of linking inactive_since on the standby for synced slots to
> the actual LSNs (or other slot parameters) being updated or not looks
> more complicated, and might not go well with the end user.  However,
> we need to be able to say why we don't invalidate synced slots due to
> inactive timeout unlike the wal_removed invalidation that can happen
> right now on the standby for synced slots. This leads us to define
> actually what a slot being active means. Is syncing the data from the
> remote slot considered as the slot being active?
> 
> On the other hand, it may not sound great if we don't invalidate
> synced slots due to inactive timeout even though they hold resources
> such as WAL and XIDs.

Right and the "only" benefit then would be to give an idea as to when the last
sync did occur on the local slot.

Regards,

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






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  Subject: Re: Introduce XID age and inactive timeout based replication slot invalidation
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