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help / color / mirror / Atom feedFrom: Nathan Bossart <[email protected]>
To: Peter Eisentraut <[email protected]>
Cc: pgsql-hackers <[email protected]>
Subject: Re: pg_upgrade: Support for upgrading to checksums enabled
Date: Tue, 27 Aug 2024 16:56:53 -0500
Message-ID: <Zs5LpYAVNks8B6oZ@nathan> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>
On Mon, Aug 26, 2024 at 08:23:44AM +0200, Peter Eisentraut wrote:
> The purpose of this patch is to allow using pg_upgrade between clusters that
> have different checksum settings. When upgrading between instances with
> different checksum settings, the --copy (default) mode automatically sets
> (or unsets) the checksum on the fly.
>
> This would be particularly useful if we switched to enabling checksums by
> default, as [0] proposes, but it's also useful without that.
Given enabling checksums can be rather expensive, I think it makes sense to
add a way to do it during pg_upgrade versus asking folks to run
pg_checksums separately. I'd anticipate arguments against enabling
checksums automatically, but as you noted, we can move it to a separate
option (e.g., --copy --enable-checksums). Disabling checksums with
pg_checksums is fast because it just updates pg_control, so I don't see any
need for --disable-checkums in pg_upgrade.
> - Windows has a separate code path in the --copy mode. I don't know the
> reasons or advantages of that. So it's not clear how the checksum rewriting
> mode should be handled in that case. We could switch to the non-Windows
> code path in that case, but then the performance difference between the
> normal path and the checksum-rewriting path is even more unclear.
AFAICT the separate Windows path dates back to before pg_upgrade was first
added to the Postgres tree, and unfortunately I couldn't find any
discussion about it.
--
nathan
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To: [email protected]
Cc: [email protected], [email protected]
Subject: Re: pg_upgrade: Support for upgrading to checksums enabled
In-Reply-To: <Zs5LpYAVNks8B6oZ@nathan>
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