From: | Bharath Rupireddy <bharath(dot)rupireddyforpostgres(at)gmail(dot)com> |
---|---|
To: | Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>, Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
Subject: | Re: add log messages when replication slots become active and inactive (was Re: Is it worth adding ReplicationSlot active_pid to ReplicationSlotPersistentData?) |
Date: | 2022-05-05 09:27:29 |
Message-ID: | CALj2ACWDA9Poe3WPm-rAp3in_pYAA+iSptXZuMDgzsw9QRaBEg@mail.gmail.com |
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Lists: | pgsql-hackers |
On Fri, Apr 29, 2022 at 4:02 PM Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> wrote:
>
> If I read the code right, this patch emits logs when
> pg_logical_slot_get_changes and pg_replication_slot_advance SQL
> functions are called. Is this desirable/useful, for the use case you
> stated at start of thread? I think it is most likely pointless. If you
> get rid of those, then the only acquisitions that would log messages are
> those in StartReplication and StartLogicalReplication. So I wonder if
> it would be better to leave the API of ReplicationSlotAcquire() alone,
> and instead make StartReplication and StartLogicalReplication
> responsible for those messages.
>
> I didn't look at the release-side messages you're adding, but I suppose
> it should be symmetrical.
Adding the messages right after ReplicationSlotAcquire in the
StartReplication and StartLogicalReplication looks okay, but, if we
just add "released replication slot \"%s\" for logical/physical
replication". in StartReplication and StartLogicalReplication right
after ReplicationSlotRelease, how about ReplicationSlotRelease in
WalSndErrorCleanup and ReplicationSlotShmemExit?
The whole idea is to get to know when and how much time a slot was
inactive/unused when log_replication_commands is set to true.
We can think of adding a timestamp column to on-disk replication slot
data but that will be too much.
Regards,
Bharath Rupireddy.
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