Horton

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

John Naylor <johncnaylorls@gmail.com>

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From: John Naylor <johncnaylorls@gmail.com>
To: Masahiko Sawada <sawada.mshk@gmail.com>
Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>, Nathan Bossart <nathandbossart@gmail.com>, Andres Freund <andres@anarazel.de>, Matthias van de Meent <boekewurm+postgres@gmail.com>, Yura Sokolov <y.sokolov@postgrespro.ru>
Date: 2024-01-17T00:20:21Z
Lists: pgsql-hackers 
On Tue, Jan 16, 2024 at 1:18 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:
> Just changing "items" to be the local tidstore struct could make the
> code tricky a bit, since max_bytes and num_items are on the shared
> memory while "items" is a local pointer to the shared tidstore.

Thanks for trying it this way! I like the overall simplification but
this aspect is not great.
Hmm, I wonder if that's a side-effect of the "create" functions doing
their own allocations and returning a pointer. Would it be less tricky
if the structs were declared where we need them and passed to "init"
functions?

That may be a good idea for other reasons. It's awkward that the
create function is declared like this:

#ifdef RT_SHMEM
RT_SCOPE RT_RADIX_TREE *RT_CREATE(MemoryContext ctx, Size max_bytes,
dsa_area *dsa,
int tranche_id);
#else
RT_SCOPE RT_RADIX_TREE *RT_CREATE(MemoryContext ctx, Size max_bytes);
#endif

An init function wouldn't need these parameters: it could look at the
passed struct to know what to do.

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