lyne7-sc opened a new pull request, #20243:
URL: https://github.com/apache/datafusion/pull/20243
## Which issue does this PR close?
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- Closes #.
## Rationale for this change
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The current implementation of `array_union` and `array_intersect` performs
`RowConverter::convert_columns()` on a per-row basis, which introduces
avoidable overhead due to repeated conversions and intermediate allocations.
This PR improves performance by:
1. converting all list values to rows in a batch
2. reusing hash sets across iterations
3. removing the `sorted().dedup()` pattern in favor of hash-based set
operations
## What changes are included in this PR?
Refactored the internal set operation implementation to use batch row
conversion and a single-pass construction of result arrays.
### Benchmarks
```
group before
optimized
----- ------
---------
array_intersect/high_overlap/10 2.99 1442.0±99.94µs ? ?/sec
1.00 481.6±21.45µs ? ?/sec
array_intersect/high_overlap/100 1.90 9.5±0.63ms ? ?/sec
1.00 5.0±0.09ms ? ?/sec
array_intersect/high_overlap/50 2.01 5.3±0.41ms ? ?/sec
1.00 2.6±0.05ms ? ?/sec
array_intersect/low_overlap/10 3.47 1288.1±72.39µs ? ?/sec
1.00 371.4±14.08µs ? ?/sec
array_intersect/low_overlap/100 2.35 9.2±0.43ms ? ?/sec
1.00 3.9±0.08ms ? ?/sec
array_intersect/low_overlap/50 2.45 5.1±0.41ms ? ?/sec
1.00 2.1±0.07ms ? ?/sec
array_union/high_overlap/10 4.01 1593.1±292.17µs ? ?/sec
1.00 396.9±13.43µs ? ?/sec
array_union/high_overlap/100 2.54 9.8±0.18ms ? ?/sec
1.00 3.9±0.11ms ? ?/sec
array_union/high_overlap/50 2.65 5.4±0.10ms ? ?/sec
1.00 2.0±0.07ms ? ?/sec
array_union/low_overlap/10 3.74 1622.7±96.50µs ? ?/sec
1.00 434.3±17.87µs ? ?/sec
array_union/low_overlap/100 2.39 10.3±0.92ms ? ?/sec
1.00 4.3±0.11ms ? ?/sec
array_union/low_overlap/50 2.63 5.8±0.27ms ? ?/sec
1.00 2.2±0.11ms ? ?/sec
```
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## Are these changes tested?
Yes. Existing SQL logic tests updated to reflect new output order.
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## Are there any user-facing changes?
Yes. The output order may differ from the previous implementation.
Previously, results were implicitly sorted due to the use of
`sorted().dedup()`. The new implementation preserves the order of first
appearance within each list.
This is a user-visible behavioral change, but it is consistent with typical
SQL set operation semantics, which do not guarantee a specific output order.
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