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: 2023-08-28T07:19:50Z
Lists: pgsql-hackers 
On Sun, Aug 27, 2023 at 7:53 PM Masahiko Sawada <sawada.mshk@gmail.com>
wrote:
>
> I've updated the regression tests for tidstore so that it uses SQL
> functions to add blocks/offsets and dump its contents. The new test
> covers the same test coverages but it's executed using SQL functions
> instead of executing all tests in one SQL function.

This is much nicer and more flexible, thanks! A few questions/comments:

tidstore_dump_tids() returns a string -- is it difficult to turn this into
a SRF, or is it just a bit more work?

The lookup test seems fine for now. The output would look nicer with an
"order by tid".

I think we could have the SQL function tidstore_create() take a boolean for
shared memory. That would allow ad-hoc testing without a recompile, if I'm
not mistaken.

+SELECT tidstore_set_block_offsets(blk, array_agg(offsets.off)::int2[])
+  FROM blocks, offsets
+  GROUP BY blk;
+ tidstore_set_block_offsets
+----------------------------
+
+
+
+
+
+(5 rows)

Calling a void function multiple times leads to vertical whitespace, which
looks a bit strange and may look better with some output, even if
irrelevant:

-SELECT tidstore_set_block_offsets(blk, array_agg(offsets.off)::int2[])
+SELECT row_number() over(order by blk), tidstore_set_block_offsets(blk,
array_agg(offsets.off)::int2[])

 row_number | tidstore_set_block_offsets
------------+----------------------------
          1 |
          2 |
          3 |
          4 |
          5 |
(5 rows)

--
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