Date: Fri, 21 Apr 2023 14:43:47 -0700
From: Nathan Bossart <nathandbossart@gmail.com>
To: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Cc: zhjwpku@gmail.com, xu.xw2008@163.com, pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #17903: There is a bug in the KeepLogSeg()
Message-ID: <20230421214347.GA1441786@nathanxps13>
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On Fri, Apr 21, 2023 at 10:42:31AM +0900, Kyotaro Horiguchi wrote:
> From what I understand, the XLogSegNo calculations are designed
> without considering the actual value range. Basically, it assumes that
> (XLogSegNo + <any positive int>) can overflow.  If we take the actual
> value range into account, we can make that change.
> 
> The choice lies on whether we assume the actual value range or not.

Yeah, after staring at this some more, I think your proposed fix is the way
to go.  Alternatively, we could adjust the conditional for the
max_slot_wal_keep_size block to

	if (keep != InvalidXLogRecPtr && keep < recptr)

but AFAICT that yields the exact same behavior.

-- 
Nathan Bossart
Amazon Web Services: https://aws.amazon.com