Date: Wed, 18 Oct 2023 11:13:01 +0900 (JST)
Message-Id: <20231018.111301.602565389803838288.horikyota.ntt@gmail.com>
To: david@pgmasters.net
Cc: thomas.munro@gmail.com, michael@paquier.xyz,
 pgsql-hackers@postgresql.org, sfrost@snowman.net
Subject: Re: The danger of deleting backup_label
From: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
In-Reply-To: <0f948866-7caf-0759-d53c-93c3e266ec3f@pgmasters.net>
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At Tue, 17 Oct 2023 16:16:42 -0400, David Steele <david@pgmasters.net> wrote in 
> Given that the above can't be back patched, I'm thinking we don't need
> backup_label at all going forward. We just write the values we need
> for recovery into pg_control and return *that* from pg_backup_stop()
> and tell the user to store it with their backup. We already have
> "These files are vital to the backup working and must be written byte
> for byte without modification, which may require opening the file in
> binary mode." in the documentation so dealing with pg_control should
> not be a problem. pg_control also has a CRC so we will know if it gets
> munged.

I'm somewhat perplexed regarding the objective of this thread.

This thread began with the intent of preventing users from removing
the backup_label from a backup. At the beginning, the proposal aimed
to achieve this by injecting an invalid value to pg_control file
located in the generated backup. However, this (and previous) proposal
seems to deviate from that initial objective. It now eliminates the
need to be concerned about the pg_control version that is coped into
the generated backup. However, if someone removes the backup_label
from a backup, the initial concerns could still surface.

regards.

-- 
Kyotaro Horiguchi
NTT Open Source Software Center