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: 2022-11-16T05:17:23Z
Lists: pgsql-hackers 
On Wed, Nov 16, 2022 at 11:46 AM John Naylor <john.naylor@enterprisedb.com>
wrote:
>
>
> On Tue, Nov 15, 2022 at 11:59 AM Masahiko Sawada <sawada.mshk@gmail.com>
wrote:
> > Thanks! Please let me know if there is something I can help with.
>
> I didn't get very far because the tests fail on 0004 in rt_verify_node:
>
> TRAP: failed Assert("n4->chunks[i - 1] < n4->chunks[i]"), File:
"../src/backend/lib/radixtree.c", Line: 2186, PID: 18242

Actually I do want to offer some general advice. Upthread I recommended a
purely refactoring patch that added the node-pointer struct but did nothing
else, so that the DSA changes would be smaller. 0004 attempted pointer
tagging in the same commit, which makes it no longer a purely refactoring
patch, so that 1) makes it harder to tell what part caused the bug and 2)
obscures what is necessary for DSA pointers and what was additionally
necessary for pointer tagging. Shared memory support is a prerequisite for
a shippable feature, but pointer tagging is (hopefully) a performance
optimization. Let's keep them separate.

--
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