Re: Make tuple deformation faster

On Tue, 16 Jul 2024 at 00:13, Matthias van de Meent
<boekewurm+postgres(at)gmail(dot)com> wrote:
>
> On Tue, 2 Jul 2024 at 02:23, David Rowley <dgrowleyml(at)gmail(dot)com> wrote:
> > I'm happy to keep going with this version of the patch
>
> +1, go for it.

I've attached an updated patch series which are a bit more polished
than the last set. I've attempted to document the distinction between
FormData_pg_attribute and the abbreviated struct and tried to give an
indication of which one should be used.

Apart from that, changes include:

* I pushed the v1-0001 patch, so that's removed from the patch series.
* Rename TupleDescDeformAttr struct. It's now called CompactAttribute.
* Rename TupleDescDeformAttr() macro. It's now called TupleDescCompactAttr()
* Other macro renaming. e.g. ATT_IS_PACKABLE_FAST to COMPACT_ATTR_IS_PACKABLE
* In 0003, renamed CompactAttribute.attalign to attalignby to make it
easier to understand the distinction between the align char and the
number of bytes.
* Added 0004 patch to remove pg_attribute.attcacheoff.

There are a few more things that could be done to optimise a few more
things. For example, a bunch of places still use att_align_nominal().
With a bit more work, these could use att_nominal_alignby(). I'm not
yet sure of the cleanest way to do this. Adding alignby to the
typecache might be one way, or maybe just a function that converts the
attalign to the number of bytes. This would be useful in all places
where att_align_nominal() is used in loops, as converting the char to
the number of bytes would only be done once rather than once per loop.
I feel like this patch series is probably big enough for now, so I'd
like to opt for those improvements to take place as follow-on work.

I'll put this up for the CF bot to run with for a bit as the patch has
needed a rebase since I pushed the v1-0001 patch.

David