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From: Joe Conway <[email protected]>
To: Andrey Stikheev <[email protected]>
To: Tom Lane <[email protected]>
Cc: [email protected]
Subject: Re: Performance degradation in Index searches with special characters
Date: Sun, 6 Oct 2024 13:45:15 -0400
Message-ID: <[email protected]> (raw)
In-Reply-To: <CALM5VP-GPRXcxs5BEfyxmsYDsHb4K4y+VST00wZGzizhEVvUsA@mail.gmail.com>
References: <CALM5VP9ePykYMnz+0xf_+OKjV_raeHNWzerCBwE5ykRSCcd+AA@mail.gmail.com>
	<[email protected]>
	<CALM5VP-GPRXcxs5BEfyxmsYDsHb4K4y+VST00wZGzizhEVvUsA@mail.gmail.com>

On 10/6/24 13:28, Andrey Stikheev wrote:
> Thanks for your feedback. After looking into it further, it seems the 
> performance issue is indeed related to the default collation settings, 
> particularly when handling certain special characters like |<| in the 
> glibc |strcoll_l| function. This was confirmed during my testing on 
> Debian 12  with glibc version 2.36 (this OS and glibc are being used in 
> our office's Docker image: https://hub.docker.com/_/postgres <https:// 
> hub.docker.com/_/postgres>).

This is not surprising. There is a performance regression that started 
in glibc 2.21 with regard to sorting unicode. Test with RHEL 7.x (glibc 
2.17) and I bet you will see comparable results to ICU. The best answer 
in the long term, IMHO, is likely to use the new built-in collation just 
released in Postgres 17.

-- 
Joe Conway
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com





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