Message-ID: <938e2d16-4449-413b-a2fc-2595e732e3e1@oss.nttdata.com>
Date: Thu, 26 Jun 2025 17:03:32 +0900
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Subject: Re: Mention idle_replication_slot_timeout in pg_replication_slots
 docs
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To: Nisha Moond <nisha.moond412@gmail.com>
Cc: pgsql-docs@lists.postgresql.org
References: <78b34e84-2195-4f28-a151-5d204a382fdd@oss.nttdata.com>
 <CABdArM5r8wD8w1dTMh+ozXZw5TbiWRYHzrc2tCy6PNOsffHvLA@mail.gmail.com>
From: Fujii Masao <masao.fujii@oss.nttdata.com>
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On 2025/06/26 15:46, Nisha Moond wrote:
> On Wed, Jun 25, 2025 at 9:56=E2=80=AFPM Fujii Masao <masao.fujii@oss.nt=
tdata.com> wrote:
>>
>> Hi,
>>
>> The pg_replication_slots documentation mentions only max_slot_wal_keep=
_size
>> as a condition under which the wal_status column can show unreserved o=
r lost.
>> However, since commit ac0e33136ab, idle_replication_slot_timeout can a=
lso
>> cause this behavior when it is set. This has not been documented yet.
>> https://www.postgresql.org/docs/devel/view-pg-replication-slots.html
>>
>=20
> +1 to the doc update.

Thanks for the review!


>> So, how about updating the documentation to also mention
>> idle_replication_slot_timeout as a factor that can cause wal_status to
>> become unreserved or lost? Patch attached.
>>
>=20
> Since idle_replication_slot_timeout can only cause wal_status to
> become 'lost' and not 'unreserved', perhaps we can reword the sentence
> slightly for clarity, suggestion -
> "The last two states are seen when max_slot_wal_keep_size is
> non-negative and, the 'lost' state may also appear when
> idle_replication_slot_timeout is greater than zero."

I was thinking that when idle_replication_slot_timeout triggers,
the following functions are called, and that wal_status can become
"unreserved" before ReplicationSlotRelease() runs. It's very short
period, though. Am I wrong?

ReplicationSlotMarkDirty();
ReplicationSlotSave();
ReplicationSlotRelease();

Regards,

--=20
Fujii Masao
NTT DATA Japan Corporation