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

On Wed, Feb 11, 2026 at 04:27:50PM +0300, Nazir Bilal Yavuz wrote:
> I am sharing a v6 which implements (1). My benchmark results show
> almost no difference for the special-character cases and a nice
> improvement for the no-special-character cases.

Thanks!

> + /* Initialize SIMD variables */
> + cstate->simd_enabled = false;
> + cstate->simd_initialized = false;

> + /* Initialize SIMD on the first read */
> + if (unlikely(!cstate->simd_initialized))
> + {
> + cstate->simd_initialized = true;
> + cstate->simd_enabled = true;
> + }

Why do we do this initialization in CopyReadLine() as opposed to setting
simd_enabled to true when initializing cstate in BeginCopyFrom()? If we
can initialize it in BeginCopyFrom, we could probably remove
simd_initialized.

> + if (cstate->simd_enabled)
> + result = CopyReadLineText(cstate, is_csv, true);
> + else
> + result = CopyReadLineText(cstate, is_csv, false);

I know we discussed this upthread, but I'd like to take a closer look at
this to see whether/why it makes such a big difference. It's a bit awkward
that CopyReadLineText() needs to manage both its local simd_enabled and
cstate->simd_enabled.

+ /* Load a chunk of data into a vector register */
+ vector8_load(&chunk, (const uint8 *) &copy_input_buf[input_buf_ptr]);

As mentioned upthread [0], I think it's worth testing whether processing
multiple vectors worth of data in each loop iteration is worthwhile.

[0] https://postgr.es/m/aSTVOe6BIe5f1l3i%40nathan

--
nathan