Horton

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

Masahiko Sawada <sawada.mshk@gmail.com>

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From: Masahiko Sawada <sawada.mshk@gmail.com>
To: John Naylor <john.naylor@enterprisedb.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: 2022-11-15T04:58:29Z
Lists: pgsql-hackers 
On Mon, Nov 14, 2022 at 10:00 PM John Naylor
<john.naylor@enterprisedb.com> wrote:
>
> On Mon, Nov 14, 2022 at 3:44 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:
> >
> > 0004 patch is a new patch supporting a pointer tagging of the node
> > kind. Also, it introduces rt_node_ptr we discussed so that internal
> > functions use it rather than having two arguments for encoded and
> > decoded pointers. With this intermediate patch, the DSA support patch
> > became more readable and understandable. Probably we can make it
> > smaller further if we move the change of separating the control object
> > from radix_tree to the main patch (0002). The patch still needs to be
> > polished but I'd like to check if this idea is worthwhile. If we agree
> > on this direction, this patch will be merged into the main radix tree
> > implementation patch.
>
> Thanks for the new patch set. I've taken a very brief look at 0004 and I think the broad outlines are okay. As you say it needs polish, but before going further, I'd like to do some experiments of my own as I mentioned earlier:
>
> - See how much performance we actually gain from tagging the node kind.
> - Try additional size classes while keeping the node kinds to only four.
> - Optimize node128 insert.
> - Try templating out the differences between local and shared memory. With local memory, the node-pointer struct would be a union, for example. Templating would also reduce branches and re-simplify some internal APIs, but it's likely that would also make the TID store and/or vacuum more complex, because at least some external functions would be duplicated.

Thanks! Please let me know if there is something I can help with.

In the meanwhile, I'd like to make some progress on the vacuum
integration and improving the test coverages.

Regards,

-- 
Masahiko Sawada
Amazon Web Services: https://aws.amazon.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