Skip to content

Fix Dict rewrites over unreferenced values - #11169

Merged
blaginin merged 4 commits into
developfrom
db/dict-unreferenced-values-tests
Nov 12, 2026
Merged

blaginin merged 4 commits into
developfrom
db/dict-unreferenced-values-tests

Conversation

@blaginin

@blaginin blaginin commented Nov 3, 2026

Copy link
Copy Markdown
Member

Prevent dictionary cast and scalar-function rewrites from failing on unreferenced values, with regression coverage for both cases.

blaginin and others added 2 commits November 3, 2026 17:21
Slicing, filtering or taking a dictionary keeps the whole values array and
only selects codes, so values that no remaining row references stay in the
dictionary. `CastReduce for Dict` and `DictionaryScalarFnCodesPullUpRule`
then apply a fallible function to every value, and a narrowing cast or a
division fails on a value that row-wise evaluation would never visit.

Both tests build valid arrays with the public constructors and fail today:
the cast reports "value exceeds target range" for rows [1, 1, 1], and the
division reports "division by zero" for [8, 8, 8] / [2, 2, 2].

Co-Authored-By: Claude Mythos 5.1 <[email protected]>
Signed-off-by: blaginin <[email protected]>
Keep value-changing casts on dictionary rows unless all values are known to be referenced. Preserve outer-nullability rewrites with the existing validity guard.

Apply the same fallibility guard to shared-code scalar-function rewrites and cover safe rewrites and errors on referenced values.

Signed-off-by: blaginin <[email protected]>
@blaginin blaginin self-assigned this Nov 3, 2026
@blaginin
blaginin marked this pull request as ready for review November 3, 2026 18:15
@blaginin blaginin added the changelog/chore A trivial change label Nov 3, 2026
@codspeed

codspeed Bot commented Nov 3, 2026 •

Copy link
Copy Markdown

Merging this PR will not alter performance

2 warnings

⚠️ Walltime results may be unreliable

Some benchmarks used the Walltime instrument outside CodSpeed Macro Runners, which can make the results inconsistent.

Learn more about Macro Runners

See affected benchmarks

⚠️ 3 benchmarks are dominated by system calls

System calls cannot be simulated consistently and are left out of the measure. The reported value understates the real cost. Switch to the Walltime instrument to measure them.

Learn more about system calls

See affected benchmarks

✅ 1921 untouched benchmarks
⏩ 50 skipped benchmarks1


Comparing db/dict-unreferenced-values-tests (999dd0b) with develop (dcada48)

Open in CodSpeed

Footnotes

  1. 50 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

connortsui20 added a commit that referenced this pull request Nov 3, 2026
## Summary

Follow-up to #11110. Keep the remaining noisy cases out of automatic
CodSpeed runs while preserving them for local benchmarks.

The Python scalar exclusions in #11110 never took effect because the
runner exports simulation as `instrumentation`, while the fixture
checked for `simulation`. Use the plugin's resolved mode so these cases
are actually skipped.

## Changes

- Allow a trailing comma in `#[divan::bench(...)]` when the CPU-feature
macro appends its options. The multiline bitpacked take definition
covers this case in CI builds.
- Share the resolved simulation check between the scalar and filter
fixtures. Also skip the 2 integer one-shot filtered scans that still
report system calls under simulation.
- Keep AVX2 bitpacked take with 80 selections local after batching still
produced a regression alert. Retain the 64-selection case and both
AVX-512 cases in CI.
- Keep AVX-512 nullable integer comparison local because its minimum
changes by more than 10% while its median stays stable.
- Keep the small random power-law boolean filter and the large
correlated power-law boolean filter local under simulation. The former
has repeated unexplained changes, and the latter repeatedly makes system
calls that simulation cannot measure.

<details>
<summary>Evidence from recent PR reports</summary>

Reviewed 40 CodSpeed report comments updated between November 2 at 19:28
UTC and November 3 at 19:28 UTC, including their comparison revisions
and the affected measurement modes.

| Case | Evidence |
| --- | --- |
| Python integer scalar scans |
[#11154](#11154 (comment))
still reports the repeated scan's 10 system calls. [A develop run after
#11110](https://github.com/vortex-data/vortex/actions/runs/41677647530/job/126062463160)
executes both integer scalar cases instead of skipping them. The [runner
exports the legacy `instrumentation`
value](https://github.com/CodSpeedHQ/codspeed/blob/main/crates/runner-shared/src/measurement_mode.rs),
which pytest-codspeed 5.0.3 normalizes to simulation. |
| Python integer filtered scans |
[#11130](#11130 (comment))
reports 30 system calls totaling 14.3 ms in `test_scan_filter[int]`.
[#11138](#11138 (comment))
reports 30 calls totaling 16.3 ms in
`test_scan_filter_to_arrow_array[int]`. |
| AVX2 `threshold[80]` |
[#11004](#11004 (comment))
compares `f7b5b1d864` with `e59b236d7b`: 2.183 to 2.531 µs, reported as
a 13.75% regression. Both use 1000 samples of 16 iterations. The head
median is 2.556 µs, so this is not just a single outlying minimum. The
PR does not change the fastlanes code or benchmark. |
| AVX-512 `lt_i64_nullable` |
[#11168](#11168 (comment))
reports 7.342 to 8.217 µs. Several unrelated CUDA PRs report the
opposite direction, including
[#10872](#10872 (comment)),
at 8.208 to 7.348 µs. Their head medians remain around 8.3 to 8.5 µs. |
| Boolean `filter_powerlaw_by_random[10000]` |
[#11167](#11167 (comment))
reports a 16.2% regression,
[#11168](#11168 (comment))
a 23.56% improvement, and
[#11169](#11169 (comment))
a 13.06% regression. The cause is unknown. |
| Boolean `filter_powerlaw_by_correlated_runs[100000]` |
[#10871](#10871 (comment))
and
[#11165](#11165 (comment))
each report 2 system calls totaling about 44 µs. |

The NEON chunked-take alerts on #11090 are on a PR that changes
execution substantially, so those cases remain enabled. Other dictionary
simulation alerts need more attribution before excluding them.

</details>

CI passes formatting, Python lint and script tests, Rust lint,
default-feature and all-feature Rust builds, all 3 CPU walltime
benchmark jobs, and Python benchmarks (36 passed, 4 intentionally
skipped). The previously failed simulation shard also passes. Some
remaining CI jobs and CodSpeed performance analysis are still pending.

No local checks were run. The pre-commit and pre-push hooks were
bypassed as requested.

---------

Signed-off-by: Connor Tsui <[email protected]>
Share the primitive cast kernel’s lossless conversion check with the dictionary rewrite so widening preserves the codes even when value coverage is unknown. Exercise the rewrites with the session optimizer now that constructors are lazy.

Signed-off-by: blaginin <[email protected]>
@blaginin
blaginin merged commit 959f234 into develop Nov 12, 2026
69 checks passed
@blaginin
blaginin deleted the db/dict-unreferenced-values-tests branch November 12, 2026 12:20
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Labels

changelog/chore A trivial change

Projects

None yet

Development

Successfully merging this pull request may close these issues.

2 participants