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: 2023-01-16T10:11:32Z
Lists: pgsql-hackers 
On Mon, Jan 16, 2023 at 3:18 PM Masahiko Sawada <sawada.mshk@gmail.com>
wrote:
>
> On Mon, Jan 16, 2023 at 2:02 PM John Naylor
> <john.naylor@enterprisedb.com> wrote:
> >

> Thanks! cfbot complaints about some warnings but these are expected
> (due to unused delete routines etc). But one reported error[1] might
> be relevant with 0002 patch?

> [05:44:11.819] test_radixtree.c.obj : error LNK2001: unresolved
> external symbol pg_popcount64
> [05:44:11.819] src\test\modules\test_radixtree\test_radixtree.dll :
> fatal error LNK1120: 1 unresolved externals

Yeah, I'm not sure what's causing that. Since that comes from a debugging
function, we could work around it, but it would be nice to understand why,
so I'll probably have to experiment on my CI repo.

> ---
> +#ifndef RT_COMMON
> +#define RT_COMMON
>
> What are we using this macro RT_COMMON for?

It was a quick way to define some things only once, so they probably all
showed up in the list of things you found not undefined. It's different
from the style of simplehash.h, which is to have a local name and #undef
for every single thing. simplehash.h is a precedent, so I'll change it to
match. I'll take a look at your list, too.

> > + * Add Tids on a block to TidStore. The caller must ensure the offset
numbers
> > + * in 'offsets' are ordered in ascending order.
> >
> > Must? What happens otherwise?
>
> It ends up missing TIDs by overwriting the same key with different
> values. Is it better to have a bool argument, say need_sort, to sort
> the given array if the caller wants?

> Since it seems you're working on another cleanup, I can address the
> above comments after your work is completed. But I'm also fine with
> including them into your cleanup work.

I think we can work mostly simultaneously, if you work on tid store and
vacuum, and I work on the template. We can always submit a full patchset
including each other's latest work. That will catch rebase issues sooner.

--
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