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Subject: Re: Optimize UUID parse using SIMD
From: Chao Li <li.evan.chao@gmail.com>
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Date: Tue, 18 Aug 2026 08:17:15 +0800
Cc: Haibo Yan <tristan.yim@gmail.com>,
 PostgreSQL-development <pgsql-hackers@postgresql.org>
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To: Masahiko Sawada <sawada.mshk@gmail.com>
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> On Aug 18, 2026, at 06:20, Masahiko Sawada <sawada.mshk@gmail.com> wrote:
> 
>>>> 
>>> 
>>> I don't think the scan can be really unbounded. string_to_uuid()
>>> receives a cstring, so by the time it is called the caller has already
>>> walked or copied the whole string to produce it. So unless the
>>> unbounded scan can be reached in some path I have overlooked, I'd
>>> prefer to keep strlen() here. Happy to change it if you still think it
>>> is worth it.
>> 
>> After more thoughts, while I still don't think the scan can be
>> unbounded, using strlen() would add an extra scan just to determine we
>> use hex_decode_safe(). I'll change it to use strnlen() instead.
> 
> I've updated the patch accordingly. Please review it.
> 
> Regards,
> 
> -- 
> Masahiko Sawada
> Amazon Web Services: https://aws.amazon.com
> <v5-0001-Optimize-UUID-parse-using-SIMD.patch>

Thanks for updating the patch. V5 looks good to me.

Best regards,
--
Chao Li (Evan)
HighGo Software Co., Ltd.
https://www.highgo.com/