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Re: Can we change pg_rewind used without wal_log_hints and data_checksums - Mailing list pgsql-hackers

From	Neil Chen
Subject	Re: Can we change pg_rewind used without wal_log_hints and data_checksums
Date	January 16 17:38:35
Msg-id	CAA3qoJmvMRPRrdjyKi5sEjb4uX6ONjvDLvRLhKRye8rogacAZw@mail.gmail.com Whole thread Raw
In response to	Re: Can we change pg_rewind used without wal_log_hints and data_checksums (Movead <lchch1990@sina.cn>)
List	pgsql-hackers

Hi Movead,

It's an interesting idea.

While it’s impossible to predict exactly how much WAL we’ll need to backtrack through --

I assume it mainly depends on the duration of long-running transactions -- this approach

seems to offer an opportunity using pg_rewind without enabling wal_log_hints.

On Fri, Jan 16, 2026 at 9:28 PM Movead <lchch1990@sina.cn> wrote:

In fact the min_commited_xid and max_commited_xid is the edge transaction commited after
diverge record, so it's enough.

Given the potential large gap between transaction IDs (especially when long-running transactions are involved),

maintaining a list/bitmap struct would be worthwhile.

A minor suggestion, for an operation that may fail, I suggest retrieving the first XLOG_RUNNING_XACTS record to obtain its base_xid

before doing the deep-dig process. If the task cannot be completed (i.e., the base_xid <= min_commited_xid condition isn’t met),

we can throw an error immediately instead of waiting for all WAL records to be parsed.

From: Movead
Date: 16 January, 17:36:56
Subject: Re: Can we change pg_rewind used without wal_log_hints and data_checksums

From: David Geier
Date: 16 January, 17:42:38
Subject: Re: Hackorum - a new mailing list frontend