Horton

Re: BitmapHeapScan streaming read user and prelim refactoring

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Melanie Plageman <melanieplageman@gmail.com>
Cc: Thomas Munro <thomas.munro@gmail.com>, Tomas Vondra <tomas@vondra.me>, Nazir Bilal Yavuz <byavuz81@gmail.com>, Dilip Kumar <dilipbalaut@gmail.com>, Heikki Linnakangas <hlinnaka@iki.fi>, Pg Hackers <pgsql-hackers@postgresql.org>
Date: 2025-03-15T15:20:23Z
Lists: pgsql-hackers 
Hi,

On 2025-03-15 10:43:45 -0400, Melanie Plageman wrote:
> On Thu, Mar 13, 2025 at 5:41 PM Melanie Plageman
> <melanieplageman@gmail.com> wrote:
> >
> > Overall, I feel pretty good about merging this once Thomas merges the
> > read stream patches.
> 
> This was committed in 944e81bf99db2b5b70b, 2b73a8cd33b745c, and
> c3953226a07527a1e2.
> I've marked it as committed in the CF app.
> 
> As we continue to test the feature in the coming weeks, we can enhance
> the read stream API with any updates needed.

Really excited about this. This work has made read streams way better, making
it much easier to add future read stream users to other places!

Greetings,

Andres Freund

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.