cloud-fan opened a new pull request #28406:
URL: https://github.com/apache/spark/pull/28406
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### What changes were proposed in this pull request?
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Push the rebase logic to the lower level of the parquet vectorized reader,
to make the final code more vectorization-friendly.
### Why are the changes needed?
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Parquet vectorized reader is carefully implemented, to make it more likely
to be vectorized by the JVM. However, the newly added datetime rebase degrade
the performance a lot, as it breaks vectorization, even if the datetime values
don't need to rebase (this is very likely as dates before 1582 is rare).
### Does this PR introduce any user-facing change?
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no
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Run part of the `DateTimeRebaseBenchmark` locally. The results:
before this patch
```
[info] Load dates from parquet: Best Time(ms) Avg
Time(ms) Stdev(ms) Rate(M/s) Per Row(ns) Relative
[info]
------------------------------------------------------------------------------------------------------------------------
[info] after 1582, vec on, rebase off 2677
2838 142 37.4 26.8 1.0X
[info] after 1582, vec on, rebase on 3828
4331 805 26.1 38.3 0.7X
[info] before 1582, vec on, rebase off 2903
2926 34 34.4 29.0 0.9X
[info] before 1582, vec on, rebase on 4163
4197 38 24.0 41.6 0.6X
[info] Load timestamps from parquet: Best Time(ms) Avg
Time(ms) Stdev(ms) Rate(M/s) Per Row(ns) Relative
[info]
------------------------------------------------------------------------------------------------------------------------
[info] after 1900, vec on, rebase off 3537
3627 104 28.3 35.4 1.0X
[info] after 1900, vec on, rebase on 6891
7010 105 14.5 68.9 0.5X
[info] before 1900, vec on, rebase off 3692
3770 72 27.1 36.9 1.0X
[info] before 1900, vec on, rebase on 7588
7610 30 13.2 75.9 0.5X
```
After this patch
```
[info] Load dates from parquet: Best Time(ms) Avg
Time(ms) Stdev(ms) Rate(M/s) Per Row(ns) Relative
[info]
------------------------------------------------------------------------------------------------------------------------
[info] after 1582, vec on, rebase off 2758
2944 197 36.3 27.6 1.0X
[info] after 1582, vec on, rebase on 2908
2966 51 34.4 29.1 0.9X
[info] before 1582, vec on, rebase off 2840
2878 37 35.2 28.4 1.0X
[info] before 1582, vec on, rebase on 3407
3433 24 29.4 34.1 0.8X
[info] Load timestamps from parquet: Best Time(ms) Avg
Time(ms) Stdev(ms) Rate(M/s) Per Row(ns) Relative
[info]
------------------------------------------------------------------------------------------------------------------------
[info] after 1900, vec on, rebase off 3861
4003 139 25.9 38.6 1.0X
[info] after 1900, vec on, rebase on 4194
4283 77 23.8 41.9 0.9X
[info] before 1900, vec on, rebase off 3849
3937 79 26.0 38.5 1.0X
[info] before 1900, vec on, rebase on 7512
7546 55 13.3 75.1 0.5X
```
Date type is 30% faster if the values don't need to rebase, 20% faster if
need to rebase.
Timestamp type is 60% faster if the values don't need to rebase, no
difference if need to rebase.
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