Subject: Re: Archive directory
To: Scott Ribe <scott_ribe@elevated-dev.com>
Cc: Yambu <hyambu@gmail.com>, Ian Lawrence Barwick <barwick@gmail.com>,
 Pgsql-admin <pgsql-admin@lists.postgresql.org>
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From: MichaelDBA <MichaelDBA@sqlexec.com>
Message-ID: <5b4dcc9a-774c-8816-a8ac-b055bc340b60@sqlexec.com>
Date: Mon, 7 Dec 2020 09:08:15 -0500
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hmmm, I disagree with that statement:

The point of the archive_command is to release WALs from the WAL 
directory that have already been applied to the actual data files during 
checkpoints, and send these archived WALs elsewhere, whether it be a 
replica, another location on the master, or to a backup server like 
Barman and pgbackrest.  The ultimate goal is to preserve point in time 
recovery.

So postgres doesn't care where you send the WALs, but that you just did 
something with it so it can remove them from its own internal directory, 
pg_wal/pg_xlog.  So you can even do this: archive_command = '/bin/true' 
which actually does nothing but lets PG know it can remove that WAL from 
its WALDIR.

Regards,
Michael Vitale


Scott Ribe wrote on 12/7/2020 8:53 AM:
>> On Dec 7, 2020, at 6:47 AM, Yambu <hyambu@gmail.com> wrote:
>>
>> Does the command ,archive_cleanup_command, delete the files from the master server? i understand this config is done on the slave server
> The point of the archive command is to copy to the replica. If you're archiving on master, then using some script to copy to replica, then postgres has no way to know when it is safe to delete WAL files.
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