Date: Wed, 30 Sep 2020 00:14:26 -0700
From: Noah Misch <noah@leadboat.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: Tom Lane <tgl@sss.pgh.pa.us>,
	Tomas Vondra <tomas.vondra@2ndquadrant.com>,
	pgsql-hackers@postgresql.org
Subject: Re: Spurious "apparent wraparound" via SimpleLruTruncate() rounding
Message-ID: <20200930071426.GA1154112@rfd.leadboat.com>
References: <20200322083452.GB1918808@rfd.leadboat.com>
 <13116.1585168951@sss.pgh.pa.us>
 <20200330052809.GB2324620@rfd.leadboat.com>
 <1959.1586198769@sss.pgh.pa.us>
 <20200407041847.GA519993@rfd.leadboat.com>
 <20200525070033.GA1591335@rfd.leadboat.com>
 <20200830053433.GA3275593@rfd.leadboat.com>
 <20200907020612.GD2455@paquier.xyz>
 <20200907031421.GA3595322@rfd.leadboat.com>
 <20200930060640.GB1996@paquier.xyz>
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On Wed, Sep 30, 2020 at 03:06:40PM +0900, Michael Paquier wrote:
> On Sun, Sep 06, 2020 at 08:14:21PM -0700, Noah Misch wrote:
> > http://cfbot.cputube.org/patch_29_2026.log applies the two patches in the
> > wrong order.  For this CF entry, ignore it.
> 
> OK, thanks.  This is a bug fix, so I have moved that to the next CF
> for now.  Noah, would you prefer more reviews or are you confident
> enough to move on with this issue?

The former.  I plan to wait until a review puts this in Ready for Committer.

I'd be content if someone reviews the slru-truncate-modulo patch and disclaims
knowledge of the slru-truncate-insurance patch; I would then abandon the
latter patch.  I'm not fond of how the latter turned out, particularly the
unintended consequence in TruncateMultiXact().  (See the commit message and/or
the edit to the comment in TruncateMultiXact().)  The subtle interaction with
SerialAdd() is not great, either.