Re: VACUUM FREEZE vs plain VACUUM

From: Rui DeSousa <rui(dot)desousa(at)icloud(dot)com>
To: Ron Johnson <ronljohnsonjr(at)gmail(dot)com>
Cc: pgsql-admin <pgsql-admin(at)postgresql(dot)org>
Subject: Re: VACUUM FREEZE vs plain VACUUM
Date: 2025-07-18 01:13:58
Message-ID: 13815633-5376-4DED-9043-E14C88B1B71E@icloud.com
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> On Jul 17, 2025, at 6:03 PM, Ron Johnson <ronljohnsonjr(at)gmail(dot)com> wrote:
>
>
> Does VACUUM FREEZE do something extra or special than to defer autovacuum for an extra 50,000,000 transactions?
>

Yes. Vacuum freeze removes the xmin on tuples that no longer need it. i.e. The xmin is not required by any other in-flight transaction.

I don’t know what you mean by defer auto vacuum. Vacuum freeze is a mechanism to recycle transaction ids; not to initiate an auto vacuum.

It sounds like you have autovacuum_freeze_max_age set too low for your environment.

i.e. Here is what I currently use:

autovacuum_freeze_max_age=800000000

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