Horton

Re: BitmapHeapScan streaming read user and prelim refactoring

Melanie Plageman <melanieplageman@gmail.com>

View thread View on postgr.es
From: Melanie Plageman <melanieplageman@gmail.com>
To: Nazir Bilal Yavuz <byavuz81@gmail.com>
Cc: Dilip Kumar <dilipbalaut@gmail.com>, Tomas Vondra <tomas@vondra.me>, Heikki Linnakangas <hlinnaka@iki.fi>, Thomas Munro <thomas.munro@gmail.com>, Andres Freund <andres@anarazel.de>, Pg Hackers <pgsql-hackers@postgresql.org>
Date: 2025-01-30T20:36:12Z
Lists: pgsql-hackers

Attachments

On Thu, Jan 30, 2025 at 3:02 AM Nazir Bilal Yavuz <byavuz81@gmail.com> wrote:
>
> On Thu, 30 Jan 2025 at 00:38, Melanie Plageman
> <melanieplageman@gmail.com> wrote:
> >
> > On Wed, Jan 22, 2025 at 4:24 PM Melanie Plageman
> > <melanieplageman@gmail.com> wrote:
> > >
> > > 0001 is just the refactoring to push the setup into a helper.
> > > 0002-0003 are required refactoring of the TBMIterateResult and
> > > TBMIterator to support the read stream API.
> > > 0004 implements using the read stream API and removing the old prefetching code.
> > > 0005 removes the table_scan_bitmap_next_block() callback, as it is not
> > > really used anymore in BitmapHeapNext() to get the next block.
> > >
> > > I could use review feedback on all of them. 0001 should be ready to
> > > push once I get some review.
> >
> > Bilal mentioned offlist that 0001 had some indentation issues in one
> > of the comments. v27 attached.
>
> I have no other comments, 0001 LGTM.

Cool, thanks!

I pushed v27-0001.

Attached v28 is rebased and has a few updates/cleanup. All patches in
the set need review and I need to do some benchmarking of v28-0003.

- Melanie

Commits

  1. Fix bitmapheapscan incorrect recheck of NULL tuples

  2. Increase default maintenance_io_concurrency to 16

  3. Separate TBM[Shared|Private]Iterator and TBMIterateResult

  4. Improve read_stream.c advice for dense streams.

  5. Increase default effective_io_concurrency to 16

  6. Delay extraction of TIDBitmap per page offsets

  7. Add lossy indicator to TBMIterateResult

  8. Move BitmapTableScan per-scan setup into a helper

  9. Add and use BitmapHeapScanDescData struct

  10. Fix bitmap table scan crash on iterator release

  11. Bitmap Table Scans use unified TBMIterator

  12. Add common interface for TBMIterators

  13. Make table_scan_bitmap_next_block() async-friendly

  14. Move EXPLAIN counter increment to heapam_scan_bitmap_next_block

  15. Refactor tidstore.c iterator buffering.

  16. BitmapHeapScan: Remove incorrect assert and reset field

  17. Change BitmapAdjustPrefetchIterator to accept BlockNumber

  18. BitmapHeapScan: Use correct recheck flag for skip_fetch

  19. BitmapHeapScan: Push skip_fetch optimization into table AM

  20. BitmapHeapScan: postpone setting can_skip_fetch

  21. BitmapHeapScan: begin scan after bitmap creation

  22. Fix EXPLAIN Bitmap heap scan to count pages with no visible tuples

  23. Remove redundant snapshot copying from parallel leader to workers

  24. Remove some obsolete smgrcloseall() calls.

  25. Remove the "snapshot too old" feature.

  26. Compute XID horizon for page level index vacuum on primary.