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: 2022-12-01T07:06:26Z
Lists: pgsql-hackers 
On Wed, Nov 30, 2022 at 2:28 PM Masahiko Sawada <sawada.mshk@gmail.com>
wrote:
>
> On Fri, Nov 25, 2022 at 5:00 PM John Naylor
> <john.naylor@enterprisedb.com> wrote:

> > These hacks were my work, but I think we can improve that by having two
versions of NODE_HAS_FREE_SLOT -- one for fixed- and one for variable-sized
nodes. For that to work, in "init-node" we'd need a branch to set fanout to
zero for node256. That should be fine -- it already has to branch for
memset'ing node128's indexes to 0xFF.
>
> Since the node has fanout regardless of fixed-sized and
> variable-sized

As currently coded, yes. But that's not strictly necessary, I think.

>, only node256 is the special case where the fanout in
> the node doesn't match the actual fanout of the node. I think if we
> want to have two versions of NODE_HAS_FREE_SLOT, we can have one for
> node256 and one for other classes. Thoughts? In your idea, for
> NODE_HAS_FREE_SLOT for fixed-sized nodes, you meant like the
> following?
>
> #define FIXED_NODDE_HAS_FREE_SLOT(node, class)
>   (node->base.n.count < rt_size_class_info[class].fanout)

Right, and the other one could be VAR_NODE_...

--
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