Horton

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

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Masahiko Sawada <sawada.mshk@gmail.com>
Cc: John Naylor <john.naylor@enterprisedb.com>, Matthias van de Meent <boekewurm+postgres@gmail.com>, Yura Sokolov <y.sokolov@postgrespro.ru>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2022-07-19T02:24:36Z
Lists: pgsql-hackers 
Hi,

On 2022-07-08 11:09:44 +0900, Masahiko Sawada wrote:
> I think that at this stage it's better to define the design first. For
> example, key size and value size, and these sizes are fixed or can be
> set the arbitary size? Given the use case of buffer mapping, we would
> need a wider key to store RelFileNode, ForkNumber, and BlockNumber. On
> the other hand, limiting the key size is 64 bit integer makes the
> logic simple, and possibly it could still be used in buffer mapping
> cases by using a tree of a tree. For value size, if we support
> different value sizes specified by the user, we can either embed
> multiple values in the leaf node (called Multi-value leaves in ART
> paper) or introduce a leaf node that stores one value (called
> Single-value leaves).

FWIW, I think the best path forward would be to do something similar to the
simplehash.h approach, so it can be customized to the specific user.

Greetings,

Andres Freund

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