From: Tom Lane <tgl@sss.pgh.pa.us>
To: Fabien COELHO <coelho@cri.ensmp.fr>
cc: PostgreSQL Developers <pgsql-hackers@lists.postgresql.org>
Subject: Re: Overflow hazard in pgbench
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Comments: In-reply-to Fabien COELHO <coelho@cri.ensmp.fr>
	message dated "Mon, 28 Jun 2021 10:13:11 +0200"
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Date: Mon, 28 Jun 2021 12:43:30 -0400
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Fabien COELHO <coelho@cri.ensmp.fr> writes:
>> I suggest applying the attached in branches that have the required 
>> functions.

> The proposed patch does fix the issue in pgbench TAP test. I'd suggest to 
> add unlikely() on all these conditions, as already done elsewhere. See 
> attached version.

Done that way, though I'm skeptical that it makes any measurable
difference.

> I also recompiled after removing manually -fwrapv: Make check, pgbench TAP 
> tests and check-world all passed. I'm not sure that edge case are well 
> enough tested in postgres to be sure that all is ok just from these runs 
> though.

Yeah, I'm afraid that in most places it'd take a specifically-designed
test case to expose a problem, if there is one.

			regards, tom lane