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help / color / mirror / Atom feedFrom: Nazir Bilal Yavuz <[email protected]>
To: KAZAR Ayoub <[email protected]>
Cc: Shinya Kato <[email protected]>
Cc: [email protected]
Subject: Re: Speed up COPY FROM text/CSV parsing using SIMD
Date: Thu, 14 Aug 2025 13:29:35 +0300
Message-ID: <CAN55FZ0houfWHn8_MEEefhprZvc33jr07GrBYo+Bp2yw=TVnKA@mail.gmail.com> (raw)
In-Reply-To: <CA+K2RumC79NwWxBdofHOYo8SCSs0YCJic05Du=xOszRmoPf9FA@mail.gmail.com>
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<CA+K2RumC79NwWxBdofHOYo8SCSs0YCJic05Du=xOszRmoPf9FA@mail.gmail.com>
Hi,
On Thu, 14 Aug 2025 at 05:25, KAZAR Ayoub <[email protected]> wrote:
>
> Following Nazir's findings about 4096 bytes being the performant line length, I did more benchmarks from my side on both TEXT and CSV formats with two different cases of normal data (no special characters) and data with many special characters.
>
> Results are con good as expected and similar to previous benchmarks
> ~30.9% faster copy in TEXT format
> ~32.4% faster copy in CSV format
> 20%-30% reduces cycles per instructions
>
> In the case of doing a lot of special characters in the lines (e.g., tables with large numbers of columns maybe), we obviously expect regressions here because of the overhead of many fallbacks to scalar processing.
> Results for a 1/3 of line length of special characters:
> ~43.9% slower copy in TEXT format
> ~16.7% slower copy in CSV format
> So for even less occurrences of special characters or wider distance between there might still be some regressions in this case, a non-significant case maybe, but can be treated in other patches if we consider to not use SIMD path sometimes.
>
> I hope this helps more and confirms the patch.
Thanks for running that benchmark! Would you mind sharing a reproducer
for the regression you observed?
--
Regards,
Nazir Bilal Yavuz
Microsoft
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Subject: Re: Speed up COPY FROM text/CSV parsing using SIMD
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