Horton

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

John Naylor <john.naylor@enterprisedb.com>

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From: John Naylor <john.naylor@enterprisedb.com>
To: Masahiko Sawada <sawada.mshk@gmail.com>
Cc: Nathan Bossart <nathandbossart@gmail.com>, Andres Freund <andres@anarazel.de>, Matthias van de Meent <boekewurm+postgres@gmail.com>, Yura Sokolov <y.sokolov@postgrespro.ru>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2023-08-15T11:53:05Z
Lists: pgsql-hackers

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On Tue, Aug 15, 2023 at 9:34 AM Masahiko Sawada <sawada.mshk@gmail.com>
wrote:

> BTW cfbot reported that some regression tests failed due to OOM. I've
> attached the patch to fix it.

Seems worth doing now rather than later, so added this and squashed most of
the rest together. I wonder if that test uses too much memory in general.
Maybe using the full uint64 is too much.

> On Mon, Aug 14, 2023 at 8:05 PM John Naylor
> <john.naylor@enterprisedb.com> wrote:

> > This is possibly faster than v38-0010, but looking like not worth the
complexity, assuming the other way avoids the bug going forward.
>
> I prefer 0010 but is it worth testing with other compilers such as clang?

Okay, keeping 0010 with a comment, and leaving out 0011 for now. Clang is
aggressive about unrolling loops, so may be worth looking globally at some
point.

> > v38-0012-Use-branch-free-coding-to-skip-new-element-index.patch

> > Within noise level of v38-0011, but it's small and simple, so I like
it, at least for small arrays.
>
> Agreed.

Keeping 0012 and not 0013.

--
John Naylor
EDB: http://www.enterprisedb.com

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