From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@anarazel.de>
cc: pgsql-hackers@postgresql.org, Thomas Munro <thomas.munro@enterprisedb.com>
Subject: Re: Large writable variables
In-reply-to: <20181016063317.xjfd2dnlhy6tg5gx@alap3.anarazel.de>
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 <20181016063317.xjfd2dnlhy6tg5gx@alap3.anarazel.de>
Comments: In-reply-to Andres Freund <andres@anarazel.de>
	message dated "Mon, 15 Oct 2018 23:33:17 -0700"
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Date: Tue, 16 Oct 2018 10:16:33 -0400
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Andres Freund <andres@anarazel.de> writes:
> On 2018-10-16 01:59:00 -0400, Tom Lane wrote:
>> Also, I noticed that the biggest part of those structs are arrays of
>> FormatNode, which has been designed with complete lack of thought about
>> size or padding issues.  We can very easily cut it in half on 64-bit
>> machines.

> Heh, neat. I feel like we've paid very little attention to that in a
> myriad of places :(

Most of the time, we probably *shouldn't* pay attention to it; logical
field ordering is worth a good deal IMO.  But in a case like this,
where there are large arrays of the things and it's not very painful
to avoid padding waste, it's worth the trouble.

			regards, tom lane