Date: Thu, 15 Jul 2021 15:09:55 -0400
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Cc: jeff.janes@gmail.com, mk@071.ovh, pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #17103: WAL segments are not removed after exceeding
 max_slot_wal_keep_size
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On 2021-Jul-15, Kyotaro Horiguchi wrote:

> This is it. It is for the master branch but also applicable to 14 as
> is. Not needed for earlier version.
> I believe the test works for Windows but haven't checked.

I looked at it.  I think it is better to make the calls to 
ReplicationSlotsComputeRequiredLSN() in slot.c (which is where most other
calls to that function are).  Also we should recompute the minimum
required Xmin at that point.

Another change I did was move the "*invalidated=true" assignment to the
block where we actually invalidate the slot; in your patch you were
doing it possibly too early if the slot was in use by some other
process.  (For end effect it probably doesn't matter much, but it's
better to have it right.)

-- 
Álvaro Herrera         PostgreSQL Developer  —  https://www.EnterpriseDB.com/

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