public inbox for [email protected]
help / color / mirror / Atom feedFrom: Andrew Dunstan <[email protected]>
To: 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, 21 Aug 2025 11:47:30 -0400
Message-ID: <[email protected]> (raw)
In-Reply-To: <CAN55FZ109W90Ux_EBEqkkU2TyNqBNhdhN_1XPRGo3iiZ2L9b=A@mail.gmail.com>
References: <CAOzEurSW8cNr6TPKsjrstnPfhf4QyQqB4tnPXGGe8N4e_v7Jig@mail.gmail.com>
<CAN55FZ247JdiT8Sd1SRiyOJxk3Ei=pDCL4kpdP=HqLRjOhKf1Q@mail.gmail.com>
<CAN55FZ2AxiwSah7TiQoMB==r=JKT0bOtooCB7ov4xRrGkVmJ1A@mail.gmail.com>
<CAOzEurR5nFt=-SijfU7y0BHVcrT6RG9ovvdVfKt_uBZfEQew9w@mail.gmail.com>
<CAOzEurSqgA69er9SzhPnXwmsVpO7-piUOuOy3dXcHOi__nSQcg@mail.gmail.com>
<CA+K2RumC79NwWxBdofHOYo8SCSs0YCJic05Du=xOszRmoPf9FA@mail.gmail.com>
<CAN55FZ0houfWHn8_MEEefhprZvc33jr07GrBYo+Bp2yw=TVnKA@mail.gmail.com>
<CA+K2Ru=jHuz_Wpgar4Sobtxeb33qxx=o59ToOhZ=vpmkMqErnA@mail.gmail.com>
<CAN55FZ1J+6eM=F5GreWEBMJcNV_gifYyYY1b6xpYzun=nWPhMQ@mail.gmail.com>
<CAN55FZ109W90Ux_EBEqkkU2TyNqBNhdhN_1XPRGo3iiZ2L9b=A@mail.gmail.com>
On 2025-08-19 Tu 10:14 AM, Nazir Bilal Yavuz wrote:
> Hi,
>
> On Tue, 19 Aug 2025 at 15:33, Nazir Bilal Yavuz <[email protected]> wrote:
>> I am able to reproduce the regression you mentioned but both
>> regressions are %20 on my end. I found that (by experimenting) SIMD
>> causes a regression if it advances less than 5 characters.
>>
>> So, I implemented a small heuristic. It works like that:
>>
>> - If advance < 5 -> insert a sleep penalty (n cycles).
> 'sleep' might be a poor word choice here. I meant skipping SIMD for n
> number of times.
>
I was thinking a bit about that this morning. I wonder if it might be
better instead of having a constantly applied heuristic like this, it
might be better to do a little extra accounting in the first, say, 1000
lines of an input file, and if less than some portion of the input is
found to be special characters then switch to the SIMD code. What that
portion should be would need to be determined by some experimentation
with a variety of typical workloads, but given your findings 20% seems
like a good starting point.
cheers
andrew
--
Andrew Dunstan
EDB: https://www.enterprisedb.com
view thread (99+ messages) latest in thread
reply
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: [email protected]
Cc: [email protected], [email protected], [email protected], [email protected]
Subject: Re: Speed up COPY FROM text/CSV parsing using SIMD
In-Reply-To: <[email protected]>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by agora; see mirroring instructions
for how to clone and mirror all data and code used for this inbox