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From: Nathan Bossart <[email protected]>
To: KAZAR Ayoub <[email protected]>
Cc: Andres Freund <[email protected]>
Cc: Pg Hackers <[email protected]>
Cc: Neil Conway <[email protected]>
Cc: Manni Wood <[email protected]>
Cc: Andrew Dunstan <[email protected]>
Cc: Shinya Kato <[email protected]>
Cc: Mark Wong <[email protected]>
Cc: Nazir Bilal Yavuz <[email protected]>
Subject: Re: Speed up COPY TO text/CSV parsing using SIMD
Date: Tue, 10 Mar 2026 14:16:57 -0500
Message-ID: <abBuKalOno33MQFw@nathan> (raw)
In-Reply-To: <CA+K2Rum_QTZqTUrdMOL5hr-OOpCwGR_9Nj1z15BFObjktMOY6A@mail.gmail.com>
References: <CA+K2Runi_H2CBL0yMm3De2KqcR9RMA0HK5cLJjEhoNszC7myeg@mail.gmail.com>
	<[email protected]>
	<CA+K2Rum_QTZqTUrdMOL5hr-OOpCwGR_9Nj1z15BFObjktMOY6A@mail.gmail.com>

On Sat, Feb 14, 2026 at 04:02:21PM +0100, KAZAR Ayoub wrote:
> On Thu, Feb 12, 2026 at 10:25 PM Andres Freund <[email protected]> wrote:
>> I have a hard time believing that adding a strlen() to the handling of a
>> short column won't be a measurable overhead with lots of short attributes.
>> Particularly because the patch afaict will call it repeatedly if there are
>> any to-be-escaped characters.
> 
> [...]
> 
> 1000 columns:
> TEXT: 17% regression
> CSV: 3.4% regression
> 
> 500 columns:
> TEXT: 17.7% regression
> CSV: 3.1% regression
> 
> 100 columns:
> TEXT: 17.3% regression
> CSV: 3% regression
> 
> A bit unstable results, but yeah the overhead for worse cases like this is
> really significant, I can't argue whether this is worth it or not, so
> thoughts on this ?

I seriously doubt we'd commit something that produces a 17% regression
here.  Perhaps we should skip the SIMD paths whenever transcoding is
required.

-- 
nathan

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