andygrove opened a new pull request, #23545:
URL: https://github.com/apache/datafusion/pull/23545
> This PR was created by an LLM as a draft PR. I will mark it as ready for
review after human review.
## Which issue does this PR close?
N/A — autonomous exploratory PR.
## Rationale for this change
Replaced chrono DateTime/TimeDelta calendar arithmetic in the per-row
to_local_time hot path with an exact integer offset shift on the raw i64
timestamp, removing the TimeDelta construction, the DateTime addition, and the
convert-back per element.
## What changes are included in this PR?
Replaced chrono DateTime/TimeDelta calendar arithmetic in the per-row
to_local_time hot path with an exact integer offset shift on the raw i64
timestamp, removing the TimeDelta construction, the DateTime addition, and the
convert-back per element.
## Are these changes tested?
Correctness: unit tests + seeded differential fuzz (bit-identical Arrow
output vs `main`).
Benchmark (criterion):
- to_local_time_no_nulls_100k: 8.891% faster (base 4139190ns -> cand
3771157ns)
- to_local_time_10pct_nulls_100k: 8.45% faster (base 3828852ns -> cand
3505310ns)
Full criterion output:
```text
to_local_time_no_nulls_100k
time: [3.7694 ms 3.7712 ms 3.7741 ms]
change: [−9.2033% −8.8914% −8.6695%] (p = 0.00 <
0.05)
Performance has improved.
Found 2 outliers among 100 measurements (2.00%)
2 (2.00%) high severe
to_local_time_10pct_nulls_100k
time: [3.5037 ms 3.5053 ms 3.5080 ms]
change: [−8.5448% −8.4501% −8.3570%] (p = 0.00 <
0.05)
Performance has improved.
Found 1 outliers among 100 measurements (1.00%)
1 (1.00%) high severe
```
## Are there any user-facing changes?
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