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

Hi Manni!

On Mon, 9 Mar 2026 at 16:31, Manni Wood <manni(dot)wood(at)enterprisedb(dot)com> wrote:
>
> I was being too brief.
>
> The benchmarks I shared were absolutely with lz4 compiled in and 'default_toast_compression = lz4' set in postgresql.conf for every postgres instance I tested with. (Furthermore, I ran `show default_toast_compression` via `psql` on each postgres instance to be sure 'default_toast_compression = lz4' was really set!)
>
> Also, all were compiled using meson using `debugoptimized` which results in `-g -O2`.
>
> So those are the benchmarks that I shared.

Thanks for the clarification.

> OK, so my final question, hopefully clarified: If I run additional benchmarks where pglz is used for default_toast_compression, is it enough to use the instances I have already compiled with lz4 in them, but with 'default_toast_compression = pglz` explicitly set in postgresql.conf in a brand new data dir created by initdb? (In other words, existing data dir deleted, then initdb run to make a new data dir, then postgresql.conf edited to ensure 'default_toast_compression = pglz` explicitly set, then and only then starting up the cluster for the first time... and finally verifying via `show default_toast_compression` for good measure.)
>
> Or should I re-compile with the lz4-is-now-the-default commit completely excised?

Yes, it is clear now; thanks. You don't need to compile without the
lz4-is-now-the-default commit. You can compile with lz4 commit and set
the 'default_toast_compression = pglz' in the postgresql.conf like you
said. This should be enough.

--
Regards,
Nazir Bilal Yavuz
Microsoft