Re: [PoC] Improve dead tuple storage for lazy vacuum

On Mon, 8 Apr 2024 at 16:27, John Naylor <johncnaylorls(at)gmail(dot)com> wrote:

> On Sun, Apr 7, 2024 at 9:08 AM John Naylor <johncnaylorls(at)gmail(dot)com>
> wrote:
> >
> > I've attached a mostly-polished update on runtime embeddable values,
> > storing up to 3 offsets in the child pointer (1 on 32-bit platforms).
> > As discussed, this includes a macro to cap max possible offset that
> > can be stored in the bitmap, which I believe only reduces the valid
> > offset range for 32kB pages on 32-bit platforms. Even there, it allows
> > for more line pointers than can possibly be useful. It also splits
> > into two parts for readability. It would be committed in two pieces as
> > well, since they are independently useful.
>
> I pushed both of these and see that mylodon complains that anonymous
> unions are a C11 feature. I'm not actually sure that the union with
> uintptr_t is actually needed, though, since that's not accessed as
> such here. The simplest thing seems to get rid if the union and name
> the inner struct "header", as in the attached.
>

Provided uintptr_t is not accessed it might be good to get rid of it.

Maybe this patch also need correction in this:
+#define NUM_FULL_OFFSETS ((sizeof(uintptr_t) - sizeof(uint8) -
sizeof(int8)) / sizeof(OffsetNumber))

Regards,
Pavel