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From: vignesh C <vignesh21@gmail.com>
Date: Mon, 17 Mar 2025 12:16:11 +0530
Message-ID: 
 <CALDaNm1yY_Jth4TkfLJr88hKEgtC6vPfomNnfPnYebe0QtQECQ@mail.gmail.com>
Subject: Re: Speed up ICU case conversion by using ucasemap_utf8To*()
To: Andreas Karlsson <andreas@proxel.se>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>,
 Jeff Davis <pgsql@j-davis.com>
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On Fri, 20 Dec 2024 at 10:50, Andreas Karlsson <andreas@proxel.se> wrote:
>
> Hi,
>
> Jeff pointed out to me that the case conversion functions in ICU have
> UTF-8 specific versions which means we can call those directly if the
> database encoding is UTF-8 and skip having to convert to and from UChar.
>
> Since most people today run their databases in UTF-8 I think this
> optimization is worth it and when measuring on short to medium length
> strings I got a 15-20% speed up. It is still slower than glibc in my
> benchmarks but the gap is smaller now.
>
> SELECT count(upper) FROM (SELECT upper(('K=C3=A5lhuvud ' || i) COLLATE
> "sv-SE-x-icu") FROM generate_series(1, 1000000) i);
>
> master:  ~540 ms
> Patched: ~460 ms
> glibc:   ~410 ms
>
> I have also attached a clean up patch for the non-UTF-8 code paths. I
> thought about doing the same for the new UTF-8 code paths but it turned
> out to be a bit messy due to different function signatures for
> ucasemap_utf8ToUpper() and ucasemap_utf8ToLower() vs ucasemap_utf8ToTitle=
().

I noticed that Jeff's comments from [1] have not yet been addressed, I
have changed the commitfest entry status to "Waiting on Author",
please address them and update it to "Needs Review".
[1] - https://www.postgresql.org/message-id/72c7c2b5848da44caddfe0f20f6c7eb=
c7c0c6e60.camel@j-davis.com

Regards,
Vignesh