Date: Fri, 30 Sep 2022 15:32:57 -0700
From: Nathan Bossart <nathandbossart@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: 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>,
	Michael Paquier <michael@paquier.xyz>,
	Robert Haas <robertmhaas@gmail.com>,
	"pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Subject: Re: predefined role(s) for VACUUM and ANALYZE
Message-ID: <20220930223257.GA190214@nathanxps13>
References: <20220920235010.GB378596@nathanxps13>
 <Yyppg/c4SB7s1IAv@paquier.xyz>
 <20220921043126.GA382738@nathanxps13>
 <20220928185034.GA1397229@nathanxps13>
 <CAOuzzgpQtdqj2BfwheD9+fjUnVSo1cmdrQmwcr-qbvKjC5cfyg@mail.gmail.com>
 <20220928201222.GA1400058@nathanxps13>
 <20220930192350.GA171832@nathanxps13>
 <678838.1664568924@sss.pgh.pa.us>
 <20220930214728.GA177925@nathanxps13>
 <742523.1664575253@sss.pgh.pa.us>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <742523.1664575253@sss.pgh.pa.us>
Archived-At: 
 <https://www.postgresql.org/message-id/20220930223257.GA190214%40nathanxps13>
Precedence: bulk

On Fri, Sep 30, 2022 at 06:00:53PM -0400, Tom Lane wrote:
> Nathan Bossart <nathandbossart@gmail.com> writes:
>> The main one I see is AclItem, which increases from 12 bytes to 16 bytes.
> 
> ... and now requires double alignment ... did you fix its typalign?

Nope, I missed that, thanks for pointing it out.  Should we move ai_privs
to the beginning of the struct, too?  The only other similar example I see
is TimeTzADT, but that only consists of an int64 and an int32, while
AclItem starts with 2 uint32s.  While it might not be strictly necessary,
it seems like there is a small chance it could become necessary in the
future.

> We could conceivably dodge the alignment increase by splitting the 64-bit
> field into two 32-bit fields, one for base privileges and one for grant
> options.  That'd be rather invasive, so unless it leads to pleasant
> improvements in readability (which it might, perhaps) I wouldn't advocate
> for it.

Yeah, the invasiveness is the main reason I haven't tried this yet, but it
does seem like it'd improve readability.

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