Horton

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

Pavel Borisov <pashkin.elfe@gmail.com>

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From: Pavel Borisov <pashkin.elfe@gmail.com>
To: John Naylor <johncnaylorls@gmail.com>
Cc: Masahiko Sawada <sawada.mshk@gmail.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>, Nathan Bossart <nathandbossart@gmail.com>, Andres Freund <andres@anarazel.de>, Matthias van de Meent <boekewurm+postgres@gmail.com>, Yura Sokolov <y.sokolov@postgrespro.ru>
Date: 2024-04-08T12:42:01Z
Lists: pgsql-hackers 
On Mon, 8 Apr 2024 at 16:27, John Naylor <johncnaylorls@gmail.com> wrote:

> On Sun, Apr 7, 2024 at 9:08 AM John Naylor <johncnaylorls@gmail.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

Commits

  1. radixtree: Fix SIGSEGV at update of embeddable value to non-embeddable.

  2. Get rid of anonymous struct

  3. Teach radix tree to embed values at runtime

  4. Teach TID store to skip bitmap for small numbers of offsets

  5. Use bump context for TID bitmaps stored by vacuum

  6. Fix alignment of stack variable

  7. Use TidStore for dead tuple TIDs storage during lazy vacuum.

  8. Rethink create and attach APIs of shared TidStore.

  9. Fix inconsistent function prototypes with function definitions.

  10. Fix a calculation in TidStoreCreate().

  11. Fix potential integer handling issue in radixtree.h.

  12. Add TIDStore, to store sets of TIDs (ItemPointerData) efficiently.

  13. Fix link error for test_radixtree module on Windows

  14. Blind attempt to fix ODR violations

  15. Fix incorrect format specifier for int64

  16. Fix redefinition of typedefs

  17. Add template for adaptive radix tree

  18. Fix signedness error in 9f225e992 for gcc

  19. Introduce helper SIMD functions for small byte arrays

  20. Optimize vacuuming of relations with no indexes.

  21. Add bound check before bsearch() for performance

  22. Allocate consecutive blocks during parallel seqscans