GH-3516: Optimize DeltaByteArrayWriter and DeltaLengthByteArrayValuesWriter

[iemejia]

Summary

Resolves#3516.

Two related changes in the DELTA_BYTE_ARRAY write path:

1. DeltaLengthByteArrayValuesWriter: drop the unused LittleEndianDataOutputStream wrapper

The class wrapped its CapacityByteArrayOutputStream with a LittleEndianDataOutputStream that was only used by Binary.writeTo() — an extra layer of dispatch on every value that never used any LE-specific functionality (writeInt/writeLong/etc.). Binary.writeTo(arrayOut) works directly with the underlying stream.

Also adds a new overload:

publicvoidwriteBytes(byte[] data, intoffset, intlength) {
lengthWriter.writeInteger(length);
arrayOut.write(data, offset, length);
}

so callers that already have the raw bytes can avoid allocating a Binary wrapper.

2. DeltaByteArrayWriter: eliminate per-value Binary.slice() allocation in the suffix path

Tightens the suffixWriter field type from ValuesWriter to DeltaLengthByteArrayValuesWriter (it's always constructed as one) so the new raw-bytes overload is callable. The suffix call becomes:

suffixWriter.writeBytes(vb, i, vb.length - i);

instead of suffixWriter.writeBytes(v.slice(i, vb.length - i)), eliminating the ByteArraySliceBackedBinary allocation per value plus a layer of virtual dispatch.

Benchmark results

From BinaryEncodingBenchmark.encodeDeltaByteArray / encodeDeltaLengthByteArray (added in #3512):

Benchmark	Configuration	master	this PR	speedup
encodeDeltaByteArray	LOW card, len=10	0.1028 µs	0.0662 µs	1.55x
encodeDeltaByteArray	HIGH card, len=10	0.1704 µs	0.1124 µs	1.52x
encodeDeltaByteArray	LOW card, len=100	0.2079 µs	0.1678 µs	1.24x
encodeDeltaLengthByteArray	LOW card, len=10	0.0481 µs	0.0397 µs	1.21x
encodeDeltaLengthByteArray	LOW card, len=100	0.1503 µs	0.1374 µs	1.09x

Long-string cases are flat or trivial — the per-value allocation is amortized away when each value is hundreds of bytes.

How to reproduce

The JMH benchmarks cited above are being added to parquet-benchmarks in #3512. Once that lands, reproduce with:

./mvnw clean package -pl parquet-benchmarks -DskipTests \
-Dspotless.check.skip=true -Drat.skip=true -Djapicmp.skip=true
java -jar parquet-benchmarks/target/parquet-benchmarks.jar \
'BinaryEncodingBenchmark.encodeDeltaByteArray|BinaryEncodingBenchmark.encodeDeltaLengthByteArray' \
-wi 5 -i 10 -f 3

Compare runs against master (baseline) and this branch (optimized).

Validation

• parquet-column: 573 tests pass
• Built with -Dspotless.check.skip=true -Drat.skip=true -Djapicmp.skip=true

User-facing changes

None. No public API change. No file format change.

The new DeltaLengthByteArrayValuesWriter.writeBytes(byte[], int, int) overload is added on top of the existing public API.

Closes#3516

Part of a small series of focused performance PRs from work in parquet-perf. Previous: #3494, #3496, #3500, #3504, #3506, #3510, #3514. Companion benchmarks contribution: #3512.

[Fokko]

@iemejia Can you fix the linting errors?

[iemejia]

Closing in favor of #3567.

I initially submitted a series of small, focused PRs thinking they'd be easier to review. In practice the sheer number (~16 PRs, with more pending) made things harder to follow — even for me. I've regrouped the changes by encoding type / performance area so that each PR is self-contained with its own benchmarks and test coverage, which should make review and performance analysis much more straightforward.

Apologies for the churn. If you've been reviewing this PR, please continue the discussion on #3567 which supersedes it. Thank you.