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help / color / mirror / Atom feedFrom: Fujii Masao <[email protected]>
To: David Steele <[email protected]>
Cc: Hüseyin Demir <[email protected]>
Cc: Pg Hackers <[email protected]>
Subject: Re: Improve checks for GUC recovery_target_xid
Date: Thu, 5 Mar 2026 01:19:17 +0900
Message-ID: <CAHGQGwFpq5D6z+NcPhZuSazkX_PjMFE3UNKwnypNs4FRT7brDw@mail.gmail.com> (raw)
In-Reply-To: <CAHGQGwG44vZbSoBmg076G+xkR6n=Tj2=q+fVkfP7yEsyF1daFA@mail.gmail.com>
References: <[email protected]>
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On Thu, Mar 5, 2026 at 12:41 AM Fujii Masao <[email protected]> wrote:
> My earlier comment was based on my misunderstanding. I thought that only
> 32-bit transaction IDs were allowed for recovery_target_xid, and therefore
> values larger than 2^32 should be rejected.
>
> However, recovery_target_xid currently accepts both 32-bit XIDs and 64-bit
> full transaction IDs (epoch + 32-bit XID). When a 64-bit value is specified,
> only the 32-bit XID portion is used as the recovery target.
> Given this behavior, your change seems to make sense.
I'm tempted to clarify this behavior by adding something like
the following text to the description of recovery_target_xid
in config.sgml...:
-------------------------------
The value can be specified as either a 32-bit transaction ID or a 64-bit
transaction ID (consisting of an epoch and a 32-bit ID), such as the value
returned by pg_current_xact_id(). When a 64-bit transaction ID is provided,
only its 32-bit transaction ID portion is used as the recovery target.
For example, the values 4294968296 (epoch 1) and 8589935592 (epoch 2)
both refer to the same 32-bit transaction ID, 1000.
The effective transaction ID (the 32-bit portion) must be greater than
or equal to 3.
-------------------------------
Regards,
--
Fujii Masao
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To: [email protected]
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Subject: Re: Improve checks for GUC recovery_target_xid
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