Re: Speed up COPY FROM text/CSV parsing using SIMD

On Tue, Jan 13, 2026 at 1:12 PM Mark Wong <markwkm(at)gmail(dot)com> wrote:

> On Fri, Jan 09, 2026 at 05:21:45PM +0300, Nazir Bilal Yavuz wrote:
> > Were you able to understand why Mark's benchmark results are different
> > from ours?
>
> Not yet... I had some guesses, which is why I suggested the processor
> pinning
> and using a ramdisk. But we haven't tried applying all of those to my
> laptop,
> which has 3 core types, or the POWER system, which may be interesting to
> use a
> ram disk on.
>
> I'm curious though, and admittedly haven't tried looking myself yet, about
> how
> the SIMD calls might look across different processor architectures. We'll
> try
> to get that on the POWER system soon...
>
> Regards,
> Mark
> --
> Mark Wong <markwkm(at)gmail(dot)com>
> EDB https://enterprisedb.com
>

Hello!

Nazir, I'm glad you are finding the benchmarks useful. I have more! :-)

All of these benchmarks are all-in-RAM, because I do think that is the best
way of getting closest to the theoretical best and worst case scenarios.

My laptop:

master: (852558b9)

text, no special: 14996
text, 1/3 special: 17270
csv, no special: 18274
csv, 1/3 special: 23852

v3

text, no special: 11282 (24.7% speedup)
text, 1/3 special: 15748 (8.8% speedup) <-- I don't believe this but it's
what I got
csv, no special: 11571 (36.6% speedup)
csv, 1/3 special: 19934 (16.4% speedup) <-- I don't believe this but it's
what I got

v4.2

text, no special: 11139 (25.7% speedup)
text, 1/3 special: 18900 (9.4% regression)
csv, no special: 11490 (37.1% speedup)
csv, 1/3 special: 26134 (9.5% regression)

An AWS EC2 t2.2xlarge instance

master: (852558b9)

text, no special: 20677
text, 1/3 special: 22660
csv, no special: 24534
csv, 1/3 special: 30999

v3

text, no special: 17534 (15.2% speedup)
text, 1/3 special: 22816 (0.6% regression)
csv, no special: 17664 (28.0% speedup)
csv, 1/3 special: 29338 (5.3% speedup) <-- I don't believe this but it's
what I got

v4.2

text, no special: 17459 (15.5% speedup)
text, 1/3 special: 25051 (10.5% regression)
csv, no special: 17574 (28.3% speedup)
csv, 1/3 special: 32092 (3.5% regression)

An AWS EC2 t4g.2xlarge instance (using ARM processor; first test of ARM
processor!)

master: (852558b9)

text, no special: 22081
text, 1/3 special: 25100
csv, no special: 27296
csv, 1/3 special: 32344

v3

text, no special: 17724 (19.7% speedup)
text, 1/3 special: 27606 (9.9% regression) <-- yikes! We would want to test
this more
csv, no special: 17597 (35.5% speedup)
csv, 1/3 special: 32597 (0.8% regression)

v4.2

text, no special: 17674 (20% speedup)
text, 1/3 special: 25773 (2.6% regression) <-- this regression is less than
for the v3 patch? Atypical...
csv, no special: 17651 (35.3% speedup)
csv, 1/3 special: 34055 (5.3% regression)

Yes, I think I agree with you that the everything-in-RAM benchmarks will
make the regressions more pronounced, just like the everything-in-RAM
benchmarks make the improvements more pronounced.

I am not sure why the CSV regression, compared to the TXT regression (even
for the v3 patch which has smaller regressions than the v4.2 patch) is
usually worse. I probably should look over some flame graphs and see if I
can find the place where the CSV-parsing code is so much slower. The CSV
regression is actually a bit frustrating (at around 5%) because the TXT
regression, at less than 1% (for the v3 patch) is so much easier to bare.

Here are some copy-to benchmarks for the v4 patch that applies SIMD to the
copy-to code.

These were all-in-RAM tests.

My laptop

master: (852558b9)

text, no special: 2948
text, 1/3 special: 11258
csv, no special: 6245
csv, 1/3 special: 11258

v4 (copy to)

text, no special: 2126 (27.9% speedup)
text, 1/3 special: 12080 (7.3% regression) <-- did not see such a big
regression before
csv, no special: 2432 (61.0% speedup)
csv, 1/3 special: 12344 (4.0% regression) <-- did not see such a big
regression before

An AWS EC2 t2.2xlarge instance

master: (852558b9)

text, no special: 4647
text, 1/3 special: 13865
csv, no special: 5421
csv, 1/3 special: 15284

v4 (copy to)

text, no special: 2460 (47.0% speedup)
text, 1/3 special: 14023 (1.1% regression)
csv, no special: 2667 (50.7% speedup)
csv, 1/3 special: 15251 (0.2% speedup)

An AWS EC2 t4g.2xlarge instance (using ARM processor; first test of ARM
processor!)

master: (852558b9)

text, no special: 6951
text, 1/3 special: 17857
csv, no special: 7951
csv, 1/3 special: 18504

v4 (copy to)

text, no special: 3372 (51.4% speedup)
text, 1/3 special: 15713 (12.0% speedup)
csv, no special: 3233 (59.3% speedup)
csv, 1/3 special: 1622 (12.3% speedup)

Once again, the v4 patch for copy-to seems like a clearer win, though, to
be fair, there were regressions when running on my laptop. (I'm starting to
think servers or desktops are better than laptops for testing these things,
though maybe that's my bias: it just seems like the server results are
always less surprising.)

Hope you all continue to find these useful...

--
-- Manni Wood EDB: https://www.enterprisedb.com