Horton

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

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Masahiko Sawada <sawada.mshk@gmail.com>
Cc: John Naylor <john.naylor@enterprisedb.com>, Matthias van de Meent <boekewurm+postgres@gmail.com>, Yura Sokolov <y.sokolov@postgrespro.ru>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2022-07-05T08:11:26Z
Lists: pgsql-hackers 
Hi,

On 2022-07-05 16:33:29 +0900, Masahiko Sawada wrote:
> > One thing I was wondering about is trying to choose node types in
> > roughly-power-of-two struct sizes. It's pretty easy to end up with significant
> > fragmentation in the slabs right now when inserting as you go, because some of
> > the smaller node types will be freed but not enough to actually free blocks of
> > memory. If we instead have ~power-of-two sizes we could just use a single slab
> > of the max size, and carve out the smaller node types out of that largest
> > allocation.
> 
> You meant to manage memory allocation (and free) for smaller node
> types by ourselves?

For all of them basically. Using a single slab allocator and then subdividing
the "common block size" into however many chunks that fit into a single node
type.

> How about using different block size for different node types?

Not following...


Greetings,

Andres Freund

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