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 <johncnaylorls@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: 2024-03-13T14:28:54Z
Lists: pgsql-hackers 
On Wed, Mar 13, 2024 at 8:05 PM John Naylor <johncnaylorls@gmail.com> wrote:
>
> On Wed, Mar 13, 2024 at 8:39 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:
>
> > As I mentioned above, if we implement the test cases in C, we can use
> > the debug-build array in the test code. And we won't use it in AND/OR
> > operations tests in the future.
>
> That's a really interesting idea, so I went ahead and tried that for
> v71. This seems like a good basis for testing larger, randomized
> inputs, once we decide how best to hide that from the expected output.
> The tests use SQL functions do_set_block_offsets() and
> check_set_block_offsets(). The latter does two checks against a tid
> array, and replaces test_dump_tids().

Great! I think that's a very good starter.

The lookup_test() (and test_lookup_tids()) do also test that the
IsMember() function returns false as expected if the TID doesn't exist
in it, and probably we can do these tests in a C function too.

BTW do we still want to test the tidstore by using a combination of
SQL functions? We might no longer need to input TIDs via a SQL
function.

> Funnily enough, the debug array
> itself gave false failures when using a similar array in the test
> harness, because it didn't know all the places where the array should
> have been sorted -- it only worked by chance before because of what
> order things were done.

Good catch, thanks.

> I squashed everything from v70 and also took the liberty of switching
> on shared memory for tid store tests. The only reason we didn't do
> this with the radix tree tests is that the static attach/detach
> functions would raise warnings since they are not used.

Agreed to test the tidstore on shared memory.

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