Horton

Re: Adding skip scan (including MDAM style range skip scan) to nbtree

Peter Geoghegan <pg@bowt.ie>

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From: Peter Geoghegan <pg@bowt.ie>
To: Alena Rybakina <a.rybakina@postgrespro.ru>
Cc: Heikki Linnakangas <hlinnaka@iki.fi>, Masahiro Ikeda <ikedamsh@oss.nttdata.com>, Tomas Vondra <tomas@vondra.me>, Masahiro.Ikeda@nttdata.com, pgsql-hackers@lists.postgresql.org, Masao.Fujii@nttdata.com
Date: 2025-03-18T16:41:18Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. nbtree: Always set skipScan flag on rescan.

  2. meson: Build numeric.c with -ftree-vectorize.

  3. Fix "variable not found in subplan target lists" in semijoin de-duplication.

  4. Revert "nbtree: Remove useless row compare arg."

  5. nbtree: Remove useless row compare arg.

  6. Prevent premature nbtree array advancement.

  7. nbtree: tighten up array recheck rules.

  8. Avoid treating nonrequired nbtree keys as required.

  9. Adjust overstrong nbtree skip array assertion.

  10. Make NULL tuple values always advance skip arrays.

  11. Avoid extra index searches through preprocessing.

  12. Improve nbtree skip scan primitive scan scheduling.

  13. Further optimize nbtree search scan key comparisons.

  14. Add nbtree skip scan optimization.

  15. Improve nbtree array primitive scan scheduling.

  16. nbtree: Make BTMaxItemSize into object-like macro.

  17. Show index search count in EXPLAIN ANALYZE, take 2.

  18. Make parallel nbtree index scans use an LWLock.

  19. Show index search count in EXPLAIN ANALYZE.

  20. Avoid nbtree parallel scan currPos confusion.

  21. nbtree: Remove useless 'strat' local variable.

  22. Normalize nbtree truncated high key array behavior.

  23. Refactor handling of nbtree array redundancies.

  24. Fix nbtree pgstats accounting with parallel scans.

  25. Avoid parallel nbtree index scan hangs with SAOPs.

  26. Show Parallel Bitmap Heap Scan worker stats in EXPLAIN ANALYZE

  27. Enhance nbtree ScalarArrayOp execution.

  28. Skip checking of scan keys required for directional scan in B-tree

  29. Instead of using a numberOfRequiredKeys count to distinguish required

On Tue, Mar 18, 2025 at 9:37 AM Alena Rybakina
<a.rybakina@postgrespro.ru> wrote:
> Sorry, I figured it out. The Assert was added to avoid misuse of the function to reinitialize memory and to ensure that it happens when parallel_aware is positive.

Yeah. The assertion is supposed to suggest "don't worry, I didn't
forget to test parallel_aware in this function
[ExecIndexScanReInitializeDSM or ExecIndexScanReInitializeDSM], it's
just that I expect to not be called unless parallel_aware is true".

An alternative approach would have been to explicitly handle
parallel_aware=false in ExecIndexScanReInitializeDSM and
ExecIndexScanReInitializeDSM: they could just return false. That would
make ExecIndexScanReInitializeDSM and ExecIndexScanReInitializeDSM
more consistent with other nearby functions (in nodeIndexScan.c and
nodeIndexOnlyScan.c), at the cost of making the calling code (in
execParallel.c) less consistent. I really don't think that that
alternative is any better to what I actually did (I actually
considered doing things this way myself at one point), though it also
doesn't seem worse. So I'm inclined to do nothing about it now.

-- 
Peter Geoghegan