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Posted to github@arrow.apache.org by "fallintoplace (via GitHub)" <gi...@apache.org> on 2026/10/20 20:42:09 UTC
[PR] perf(parquet): fast-path constant delta bitpacked blocks [arrow-go]
fallintoplace opened a new pull request, #1396:
URL: https://github.com/apache/arrow-go/pull/1396
### What
Speed up DELTA_BINARY_PACKED encoding for constant and sparse deltas.
### Why
Zero-width miniblocks produce no payload, but the encoder still does per-value work.
### Implementation
- Encode uniform blocks without a payload.
- Skip writes for zero-width miniblocks in mixed blocks.
### Benchmark
- 65,536 values, Go 1.26.3, Apple M1 Pro, median of 5: int32 constant 416.6 → 197.8 µs/op (2.1x), sparse 420.2 → 312.1 µs/op (1.35x); int64 constant 411.5 → 193.1 µs/op (2.1x), sparse 420.7 → 314.7 µs/op (1.34x).
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Re: [PR] perf(parquet): fast-path constant delta bitpacked blocks [arrow-go]
Posted by "zeroshade (via GitHub)" <gi...@apache.org>.
zeroshade commented on code in PR #1396:
URL: https://github.com/apache/arrow-go/pull/1396#discussion_r4339819668
##########
parquet/internal/encoding/delta_bit_packing_fast_path_test.go:
##########
@@ -0,0 +1,140 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package encoding
+
+import (
+ "fmt"
+ "math"
+ "math/rand"
+ "testing"
+
+ "github.com/apache/arrow-go/v18/arrow/memory"
+ "github.com/apache/arrow-go/v18/parquet"
+ "github.com/stretchr/testify/require"
+)
+
+func TestDeltaBitPackConstantBlockWireFormat(t *testing.T) {
+ t.Run("full positive block", func(t *testing.T) {
+ values := make([]int32, 129)
+ for i := range values {
+ values[i] = 10 + int32(i)*2
+ }
+
+ enc := NewEncoder(parquet.Types.Int32, parquet.Encodings.DeltaBinaryPacked, false, nil, memory.DefaultAllocator).(*deltaBitPackEncoder[int32])
+ defer enc.Release()
+ enc.Put(values)
+
+ buf, err := enc.FlushValues()
+ require.NoError(t, err)
+ defer buf.Release()
+
+ // Block size 128, 4 miniblocks, 129 values, first value 10,
+ // minimum delta 2, then four zero bit widths and no payload.
+ require.Equal(t, []byte{0x80, 0x01, 0x04, 0x81, 0x01, 0x14, 0x04, 0, 0, 0, 0}, buf.Bytes())
+ })
+
+ t.Run("partial negative block", func(t *testing.T) {
+ values := []int64{5, 4, 3, 2, 1, 0, -1}
+ enc := NewEncoder(parquet.Types.Int64, parquet.Encodings.DeltaBinaryPacked, false, nil, memory.DefaultAllocator).(*deltaBitPackEncoder[int64])
+ defer enc.Release()
+ enc.Put(values)
+
+ buf, err := enc.FlushValues()
+ require.NoError(t, err)
+ defer buf.Release()
+
+ // The trailing miniblocks are also written as zero-width.
+ require.Equal(t, []byte{0x80, 0x01, 0x04, 0x07, 0x0a, 0x01, 0, 0, 0, 0}, buf.Bytes())
+ })
+}
+
+func testDeltaBitPackBlockRoundTrip[T int32 | int64](t *testing.T, typ parquet.Type) {
+ t.Helper()
+
+ encode := func(parts ...[]T) []byte {
+ t.Helper()
+ enc := NewEncoder(typ, parquet.Encodings.DeltaBinaryPacked, false, nil, memory.DefaultAllocator).(*deltaBitPackEncoder[T])
+ defer enc.Release()
+ for _, part := range parts {
+ enc.Put(part)
+ }
+ buf, err := enc.FlushValues()
+ require.NoError(t, err)
+ defer buf.Release()
+ return append([]byte(nil), buf.Bytes()...)
+ }
+
+ for _, n := range []int{1, 2, 31, 32, 33, 127, 128, 129, 130, 255, 257, 1001} {
+ for _, pattern := range []string{"constant", "zero", "sparse", "alternating", "random", "overflow"} {
Review Comment:
Could you add a nearly all-equal block whose only different difference is the last one, for a short block (e.g. `[0, 3, 10]`) and a full 129-value block, for both int32 and int64, with the outlier both higher and lower? Leaving the last difference out of the new all-equal check still passes all of these tests.
##########
parquet/internal/encoding/delta_bit_packing_block_bench_test.go:
##########
@@ -0,0 +1,74 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package encoding
+
+import (
+ "math/rand"
+ "testing"
+
+ "github.com/apache/arrow-go/v18/arrow/memory"
+ "github.com/apache/arrow-go/v18/parquet"
+)
+
+func benchmarkDeltaBitPackBlockFastPath[T int32 | int64](b *testing.B, typ parquet.Type, bytesPerValue int) {
+ const length = 64 * 1024
+
+ for _, pattern := range []string{"constant", "sparse", "alternating", "random"} {
+ b.Run(pattern, func(b *testing.B) {
+ values := make([]T, length)
+ rng := rand.New(rand.NewSource(42))
+ for i := 1; i < length; i++ {
+ switch pattern {
+ case "constant":
+ values[i] = values[i-1] + T(3)
+ case "sparse":
Review Comment:
Please also benchmark a smaller difference at the end of each block, e.g. step `3` except step `-7` at each block's last position. The new check scans the whole block before finding it, and then every miniblock still needs a payload. Pinned int32 runs went from 441,562–457,788 to 460,766–512,463 ns/op (about 10% slower by median). Can the extra scan be avoided, or the tradeoff documented?
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Re: [PR] perf(parquet): fast-path constant delta bitpacked blocks [arrow-go]
Posted by "zeroshade (via GitHub)" <gi...@apache.org>.
zeroshade merged PR #1396:
URL: https://github.com/apache/arrow-go/pull/1396
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