From: Tom Lane <tgl@sss.pgh.pa.us>
To: Michael Paquier <michael@paquier.xyz>
cc: Fabien COELHO <coelho@cri.ensmp.fr>,
        Michael Banck <michael.banck@credativ.de>,
        pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: pg_verify_checksums and -fno-strict-aliasing
In-reply-to: <20180831000600.GI15446@paquier.xyz>
References: <1535618100.1286.3.camel@credativ.de>
 <alpine.DEB.2.21.1808301325070.32764@lancre> <7321.1535639966@sss.pgh.pa.us>
 <20180830175652.GC15446@paquier.xyz> <12123.1535672257@sss.pgh.pa.us>
 <20180831000600.GI15446@paquier.xyz>
Comments: In-reply-to Michael Paquier <michael@paquier.xyz>
	message dated "Thu, 30 Aug 2018 17:06:00 -0700"
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-ID: <28225.1535727306.1@sss.pgh.pa.us>
Date: Fri, 31 Aug 2018 10:55:06 -0400
Message-ID: <28226.1535727306@sss.pgh.pa.us>
Precedence: bulk

Michael Paquier <michael@paquier.xyz> writes:
> On Thu, Aug 30, 2018 at 07:37:37PM -0400, Tom Lane wrote:
>> Anyway, I'll work on a patch for that, unless you were on it already?

> I have begun working on that and am less than halfway through it as I
> needed a fresh problem, however I am not sure I would be able to finish
> it today, perhaps tomorrow...  If you have time and want to press on as
> 11 would release soon, of course feel free to wrap up more quickly than
> I can.

Some of these places might be performance-critical enough that adding
a palloc/pfree cycle would not be nice.  What I was considering doing
was inventing something like

typedef union PGAlignedBuffer
{
	char	data[BLCKSZ];
	double	force_align;
} PGAlignedBuffer;

and replacing plain char[] variables with that as appropriate.
We might need one for XLOG_BLCKSZ too.

Since this'd be used in frontend as well as backend, it'd likely
have to end up in c.h, which is slightly annoying but not really
a big deal as long as we pick a nonconflicting type name.

			regards, tom lane