Horton

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

John Naylor <johncnaylorls@gmail.com>

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From: John Naylor <johncnaylorls@gmail.com>
To: Masahiko Sawada <sawada.mshk@gmail.com>
Cc: 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: 2023-12-19T07:36:52Z
Lists: pgsql-hackers 
On Tue, Dec 19, 2023 at 12:37 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:
>
> On Mon, Dec 18, 2023 at 3:41 PM John Naylor <johncnaylorls@gmail.com> wrote:
> > Let's do it in just one place. In TidStoreCreate(), do
> >
> > /* clamp max_bytes to at least the size of the empty tree with
> > allocated blocks, so it doesn't immediately appear full */
> > ts->control->max_bytes = Max(max_bytes, {rt, shared_rt}_memory_usage);
> >
> > Then we can get rid of all the worry about 1MB/2MB, 64kB, 70kB -- all that.
>
> But doesn't it mean that even if we create a shared tidstore with
> small memory, say 64kB, it actually uses 1MB?

This sounds like an argument for controlling the minimum DSA segment
size. (I'm not really in favor of that, but open to others' opinion)

I wasn't talking about that above -- I was saying we should have only
one place where we clamp max_bytes so that the tree doesn't
immediately appear full.

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