Date: Fri, 25 Aug 2023 11:18:42 +0000
From: Victor Sudakov <vas@sibptus.ru>
To: pgsql-admin@lists.postgresql.org
Subject: Temporary disabling a replica in a Patroni cluster
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Dear Colleagues,

Do you perchance know what is the correct procedure of temporarily
taking down a replica in a Patroni cluster, e.g. for 5-10 minutes of
hardware maintenance?

The problem is that after stopping the patroni process (service) on a
replica, patroni removes the corresponding physical replication slot
from the leader, and unless the wal_keep_size value is unsanely high,
the replica, when up again, cannot restart streaming because the WAL
segments are already gone from the leader.

Well, you all know:
<%%%>LOG:  started streaming WAL from primary at B4A0/E2000000 on timeline 8
<%%%>FATAL:  could not receive data from WAL stream: ERROR:  requested WAL segment 000000080000B4A0000000E2 has already been removed
<%%%>LOG:  waiting for WAL to become available at B4A0/E2002000

Do you think there is a way to tell Patroni that a replica is down
temporarily and its replication slot should not be removed?

Or, what am I missing? 

-- 
Victor Sudakov VAS4-RIPE
http://vas.tomsk.ru/
2:5005/49@fidonet