[thorfour]

Split out of #9775.

Summary

• BoundedMax/BoundedMin partial states now carry Exact/Inexact variants. A partial is Exact when no accumulated value had to be truncated to fit the byte bound.
• New AggregateFnVTable::partial_can_satisfy hook. It defaults to can_satisfy, so an aggregate can say whether one particular partial state satisfies another aggregate. An untruncated bounded partial can satisfy exact Max/Min.
• New DynAccumulator::can_satisfy exposes the hook on accumulators.

Why

#9775 records file statistics from aggregate partials. Today the legacy StatsSet path records untruncated string/binary min/max as exact through its truncation flag. DuckDB, the DuckLake COPY return stats and DataFusion all rely on that. Without this change those values would become inexact, and those consumers would drop them.

Checks

• cargo clippy -p vortex-array --all-targets --all-features -- -D warnings
• cargo +nightly-2026-09-10 fmt -p vortex-array --check
• cargo nextest run -p vortex-array: 4481 passed
• typos

[codspeed]

Merging this PR will degrade performance by 11.31%

3 warnings, 1 note

⚠️ 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

⚠️ 18 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

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⚠️ Base and head ran on different runner types

Some benchmarks with significant performance changes were compared across different runner types, so the changes might not come from the code. Run base and head on the same runner type, or use CodSpeed Macro Runners for more stable results.

Learn more about Macro Runners

Open the report in CodSpeed to investigate

ℹ️ 40 benchmarks have no flamegraph

The flamegraph wasn't generated: the symbols of the profiling trace could not be resolved, because no information about the language frames was collected.

See affected benchmarks

❌ 3 regressed benchmarks
✅ 2405 untouched benchmarks
⏩ 12 skipped benchmarks¹

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Walltime	bitpack_blocked_compress_avx2	6.7 µs	7.6 µs	-11.53%
❌	CPU Simulation	random_i128[0.01]	5.3 µs	6 µs	-11.39%
❌	CPU Simulation	test_scan_filter[int]	3.1 ms	3.4 ms	-11.01%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

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_{Comparing polarsignals:bounded-aggregate-exactness (7dcbf2a) with develop (d270200)}

Footnotes

1. 12 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. ↩