From: Jehan-Guillaume de Rorthais <jgdr@dalibo.com>
To: Thomas Munro <thomas.munro@gmail.com>
To: Peter Geoghegan <pg@bowt.ie>
Cc: Роман Литовченко <roman.lytovchenko@gmail.com>
Cc: PostgreSQL mailing lists <pgsql-bugs@lists.postgresql.org>
Subject: Re: BUG #15285: Query used index over field with ICU collation in some cases wrongly return 0 rows
Date: Sat, 13 Jun 2020 00:43:22 +0200
Message-ID: <20200613004322.3bcc37f6@firost> (raw)
In-Reply-To: <20200612184055.205f0159@firost>
References: <153201618542.1404.3611626898935613264@wrigleys.postgresql.org>
<CAH2-Wz=TGN_03qBmqgFXVhw6Kbfys-EBz4MJunzRq+RB5gL7WA@mail.gmail.com>
<CAH2-Wzkiue6PQzneBJsuDnYdUVMa5jnevVJXXkV3hR0oboOSbQ@mail.gmail.com>
<CAEepm=1-f3OuO_zA83C0x8dLFqMA+Q=RGUkyMRp4WXxjSrvbww@mail.gmail.com>
<20200610002933.6a6d482b@firost>
<20200612184055.205f0159@firost>
On Fri, 12 Jun 2020 18:40:55 +0200
Jehan-Guillaume de Rorthais <jgdr@dalibo.com> wrote:
> On Wed, 10 Jun 2020 00:29:33 +0200
> Jehan-Guillaume de Rorthais <jgdr@dalibo.com> wrote:
> [...]
> > After playing with ICU regression tests, I found functions ucol_strcollIter
> > and ucol_nextSortKeyPart are safe. I'll do some performance tests and report
> > here.
>
> I did some benchmarks. See attachment for the script and its header to
> reproduce.
>
> It sorts 935895 french phrases from 0 to 122 chars with an average of 49.
> Performance tests were done on current master HEAD (buggy) and using the patch
> in attachment, relying on ucol_strcollIter.
>
> My preliminary test with ucol_getSortKey was catastrophic, as we might
> expect. 15-17x slower than the current HEAD. So I removed it from actual
> tests. I didn't try with ucol_nextSortKeyPart though.
>
> Using ucol_strcollIter performs ~20% slower than HEAD on UTF8 databases, but
> this might be acceptable. Here are the numbers:
>
> DB Encoding HEAD strcollIter ratio
> UTF8 2.74 3.27 1.19x
> LATIN1 5.34 5.40 1.01x
>
> I plan to add a regression test soon.
Please, find in attachment the second version of the patch, with a
regression test.
Regards,
Attachments:
v2-0001-Replace-buggy-ucol_strcoll-funcs-with-ucol_strcollIt.patch (text/x-patch, 0B) download
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-bugs@postgresql.org
Cc: jgdr@dalibo.com, thomas.munro@gmail.com, pg@bowt.ie, roman.lytovchenko@gmail.com, pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #15285: Query used index over field with ICU collation in some cases wrongly return 0 rows
In-Reply-To: <20200613004322.3bcc37f6@firost>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox