Date: Tue, 20 Sep 2022 16:50:10 -0700
From: Nathan Bossart <nathandbossart@gmail.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: Robert Haas <robertmhaas@gmail.com>, Stephen Frost <sfrost@snowman.net>,
	Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>,
	"David G. Johnston" <david.g.johnston@gmail.com>,
	Kyotaro Horiguchi <horikyota.ntt@gmail.com>,
	"pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Subject: Re: predefined role(s) for VACUUM and ANALYZE
Message-ID: <20220920235010.GB378596@nathanxps13>
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 <CAOuzzgr60X+pnVphekO=WnAwGo9pTbo9ZG_GK4nFaR=Dxqd1hg@mail.gmail.com>
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On Tue, Sep 20, 2022 at 04:31:17PM -0700, Nathan Bossart wrote:
> On Tue, Sep 20, 2022 at 11:05:33AM -0700, Nathan Bossart wrote:
>> On Tue, Sep 20, 2022 at 02:45:52PM +0900, Michael Paquier wrote:
>>> Any impact for the column sizes of the catalogs holding ACL
>>> information?  Just asking while browsing the patch set.
>> 
>> Since each aclitem requires 16 bytes instead of 12, I assume so.  However,
>> in my testing, I hit a "row is too big" error with the same number of
>> aclitems in a pg_class row before and after the change.  I might be missing
>> something in my patch, or maybe I am misunderstanding how arrays of
>> aclitems are stored on disk.
> 
> Ah, it looks like relacl is compressed.  The column is marked "extended,"
> but pg_class doesn't appear to have a TOAST table, so presumably no
> out-of-line storage can be used.  I found a couple of threads about this
> [0] [1] [2].

I suppose there is some risk that folks with really long aclitem arrays
might be unable to pg_upgrade to a version with uint64 AclModes, but I
suspect that risk is limited to extreme cases (i.e., multiple thousands of
aclitems).  I'm not sure whether that's worth worrying about too much.

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