Horton

Re: How can end users know the cause of LR slot sync delays?

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: Ashutosh Sharma <ashu.coek88@gmail.com>
Cc: Shlok Kyal <shlok.kyal.oss@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2025-09-12T10:54:44Z
Lists: pgsql-hackers

Commits

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  1. Rename column slotsync_skip_at to slotsync_last_skip.

  2. Add slotsync_skip_reason column to pg_replication_slots view.

  3. Fix test failure caused by commit 76b78721ca.

  4. Fix a BF failure caused by commit 76b78721ca.

  5. Add slotsync skip statistics.

On Fri, Sep 12, 2025 at 1:07 PM Ashutosh Sharma <ashu.coek88@gmail.com> wrote:
>
> On Mon, Sep 8, 2025 at 9:52 AM Ashutosh Sharma <ashu.coek88@gmail.com> wrote:
> >
> > I think we can do that, since sync_skip_reason appears to be a
> > descriptive metadata rather than statistical data like
> > slot_sync_skip_count and last_slot_sync_skip. However, it's also true
> > that all three pieces of data are transient by nature - they will just
> > be present in the runtime.
> >
>
> After spending some more time on this, I found that maintaining
> sync_skip_reason in pg_replication_slots would make the code changes a
> bit messy and harder to maintain.
>

What exactly is your worry? It seems more logical to have
sync_skip_reason in pg_replication_slots and other two in
pg_stat_replication_slots as the latter is purely a stats view and the
sync_skip_count/last_sync_skip suits there better.

 I think storing all 3 pieces of
> information - sync_skip_reason, sync_skip_count, and last_sync_skip in
> pg_stat_replication_slots would be a cleaner solution. This way, all
> the sync-related info stays together and the code remains
> straightforward.
>

Having all the sync information together has merit but don't you think
in this case the sync_skip_reason doesn't seem to be matching with the
existing columns in pg_stat_replication_slots?

-- 
With Regards,
Amit Kapila.