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GH-34335: [C++][Parquet] Optimize Decoding DELTA_LENGTH_BYTE_ARRAY #34336

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mapleFU wants to merge 4 commits into from
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GH-34335: [C++][Parquet] Optimize Decoding DELTA_LENGTH_BYTE_ARRAY #34336

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fb83b38
Parquet: Optimize Decoding DELTA_LENGTH_BYTE_ARRAY
mapleFU Feb 24, 2023
620828a
zero-copy read
mapleFU Feb 24, 2023
dc33d36
fix ub
mapleFU Feb 24, 2023
8f624f8
Merge branch 'main' into parquet/optimize-delta-length-decoding
mapleFU Feb 28, 2023
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6 changes: 5 additions & 1 deletion cpp/src/arrow/util/bit_stream_utils.h
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Original file line number Diff line number Diff line change
Expand Up @@ -178,11 +178,15 @@ class BitReader {

/// Returns the number of bytes left in the stream, not including the current
/// byte (i.e., there may be an additional fraction of a byte).
int bytes_left() {
int bytes_left() const {
return max_bytes_ -
(byte_offset_ + static_cast<int>(bit_util::BytesForBits(bit_offset_)));
}

const uint8_t* begins() const { return buffer_; }

int64_t sum_bit_offsets() const { return byte_offset_ * 8 + bit_offset_; }

/// Maximum byte length of a vlq encoded int
static constexpr int kMaxVlqByteLength = 5;

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24 changes: 14 additions & 10 deletions cpp/src/parquet/encoding.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -2703,8 +2703,7 @@ class DeltaLengthByteArrayDecoder : public DecoderImpl,
MemoryPool* pool = ::arrow::default_memory_pool())
: DecoderImpl(descr, Encoding::DELTA_LENGTH_BYTE_ARRAY),
len_decoder_(nullptr, pool),
buffered_length_(AllocateBuffer(pool, 0)),
buffered_data_(AllocateBuffer(pool, 0)) {}
buffered_length_(AllocateBuffer(pool, 0)) {}

void SetData(int num_values, const uint8_t* data, int len) override {
num_values_ = num_values;
Expand All @@ -2713,9 +2712,10 @@ class DeltaLengthByteArrayDecoder : public DecoderImpl,
DecodeLengths();
}

// SetDecoder will be used by DeltaByteArrayDecoder.
void SetDecoder(int num_values, std::shared_ptr<::arrow::bit_util::BitReader> decoder) {
num_values_ = num_values;
decoder_ = decoder;
decoder_ = std::move(decoder);
DecodeLengths();
}

Expand All @@ -2736,21 +2736,26 @@ class DeltaLengthByteArrayDecoder : public DecoderImpl,
throw ParquetException("negative string delta length");
}
buffer[i].len = len;
if (AddWithOverflow(data_size, len, &data_size)) {
if (ARROW_PREDICT_FALSE(AddWithOverflow(data_size, len, &data_size))) {
throw ParquetException("excess expansion in DELTA_(LENGTH_)BYTE_ARRAY");
}
}
length_idx_ += max_values;

PARQUET_THROW_NOT_OK(buffered_data_->Resize(data_size));
if (decoder_->GetBatch(8, buffered_data_->mutable_data(), data_size) != data_size) {
const uint8_t* begin = decoder_->begins();
int64_t current_bits_offset = decoder_->sum_bit_offsets();
if (ARROW_PREDICT_FALSE(current_bits_offset % 8 != 0)) {
throw ParquetException("Invalid DELTA_(LENGTH_)BYTE_ARRAY");
}
int64_t current_bytes_offset = current_bits_offset / 8;
// Check overflow
if (ARROW_PREDICT_FALSE(!decoder_->Advance(static_cast<int64_t>(data_size) * 8))) {
ParquetException::EofException();
}
const uint8_t* data_ptr = buffered_data_->data();

for (int i = 0; i < max_values; ++i) {
buffer[i].ptr = data_ptr;
data_ptr += buffer[i].len;
buffer[i].ptr = begin + current_bytes_offset;
current_bytes_offset += buffer[i].len;
}
this->num_values_ -= max_values;
num_valid_values_ -= max_values;
Expand Down Expand Up @@ -2835,7 +2840,6 @@ class DeltaLengthByteArrayDecoder : public DecoderImpl,
int num_valid_values_;
uint32_t length_idx_;
std::shared_ptr<ResizableBuffer> buffered_length_;
std::shared_ptr<ResizableBuffer> buffered_data_;
};

// ----------------------------------------------------------------------
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