mapleFU commented on code in PR #14293:
URL: https://github.com/apache/arrow/pull/14293#discussion_r1050922988
##########
cpp/src/parquet/encoding.cc:
##########
@@ -2537,6 +2537,102 @@ class DeltaBitPackDecoder : public DecoderImpl, virtual
public TypedDecoder<DTyp
// ----------------------------------------------------------------------
// DELTA_LENGTH_BYTE_ARRAY
+// ----------------------------------------------------------------------
+// DeltaLengthByteArrayEncoder
+
+template <typename DType>
+class DeltaLengthByteArrayEncoder : public EncoderImpl,
+ virtual public TypedEncoder<DType> {
+ public:
+ using T = typename DType::c_type;
+
+ explicit DeltaLengthByteArrayEncoder(const ColumnDescriptor* descr,
MemoryPool* pool)
+ : EncoderImpl(descr, Encoding::DELTA_LENGTH_BYTE_ARRAY,
+ pool = ::arrow::default_memory_pool()),
+ sink_(pool),
+ length_encoder_(nullptr, pool),
+ encoded_size_{0} {}
+
+ std::shared_ptr<Buffer> FlushValues() override;
+
+ int64_t EstimatedDataEncodedSize() override { return encoded_size_; }
+
+ using TypedEncoder<DType>::Put;
+
+ void Put(const ::arrow::Array& values) override;
+
+ void Put(const T* buffer, int num_values) override;
+
+ void PutSpaced(const T* src, int num_values, const uint8_t* valid_bits,
+ int64_t valid_bits_offset) override;
+
+ protected:
+ ::arrow::BufferBuilder sink_;
+ DeltaBitPackEncoder<Int32Type> length_encoder_;
+ uint32_t encoded_size_;
+};
+
+template <>
+void DeltaLengthByteArrayEncoder<ByteArrayType>::Put(const ::arrow::Array&
values) {
+ auto src = values.data()->GetValues<ByteArray>(1);
+ Put(src, static_cast<int>(values.length()));
+}
+
+template <typename DType>
+void DeltaLengthByteArrayEncoder<DType>::Put(const T* src, int num_values) {
+ if (num_values == 0) {
+ return;
+ }
+
+ std::vector<int32_t> lengths(num_values);
Review Comment:
would construct a vector during every user `Put` be expansive? Can we cache
an array and just use `resize`?
https://en.cppreference.com/w/cpp/container/vector/resize . Seems that we
don't need to allocate a array every time we need it.
##########
cpp/src/parquet/encoding.cc:
##########
@@ -2537,6 +2537,102 @@ class DeltaBitPackDecoder : public DecoderImpl, virtual
public TypedDecoder<DTyp
// ----------------------------------------------------------------------
// DELTA_LENGTH_BYTE_ARRAY
+// ----------------------------------------------------------------------
+// DeltaLengthByteArrayEncoder
+
+template <typename DType>
Review Comment:
Seems our standard says DeltaLengthByteArray only supports BYTE_ARRAY, can
we use a fixed type or limit the `DType` here?
##########
cpp/src/parquet/encoding.cc:
##########
@@ -2537,6 +2537,102 @@ class DeltaBitPackDecoder : public DecoderImpl, virtual
public TypedDecoder<DTyp
// ----------------------------------------------------------------------
// DELTA_LENGTH_BYTE_ARRAY
+// ----------------------------------------------------------------------
+// DeltaLengthByteArrayEncoder
+
+template <typename DType>
+class DeltaLengthByteArrayEncoder : public EncoderImpl,
+ virtual public TypedEncoder<DType> {
+ public:
+ using T = typename DType::c_type;
+
+ explicit DeltaLengthByteArrayEncoder(const ColumnDescriptor* descr,
MemoryPool* pool)
+ : EncoderImpl(descr, Encoding::DELTA_LENGTH_BYTE_ARRAY,
+ pool = ::arrow::default_memory_pool()),
+ sink_(pool),
+ length_encoder_(nullptr, pool),
+ encoded_size_{0} {}
+
+ std::shared_ptr<Buffer> FlushValues() override;
+
+ int64_t EstimatedDataEncodedSize() override { return encoded_size_; }
+
+ using TypedEncoder<DType>::Put;
+
+ void Put(const ::arrow::Array& values) override;
+
+ void Put(const T* buffer, int num_values) override;
+
+ void PutSpaced(const T* src, int num_values, const uint8_t* valid_bits,
+ int64_t valid_bits_offset) override;
+
+ protected:
+ ::arrow::BufferBuilder sink_;
+ DeltaBitPackEncoder<Int32Type> length_encoder_;
+ uint32_t encoded_size_;
+};
+
+template <>
+void DeltaLengthByteArrayEncoder<ByteArrayType>::Put(const ::arrow::Array&
values) {
+ auto src = values.data()->GetValues<ByteArray>(1);
+ Put(src, static_cast<int>(values.length()));
+}
+
+template <typename DType>
+void DeltaLengthByteArrayEncoder<DType>::Put(const T* src, int num_values) {
+ if (num_values == 0) {
+ return;
+ }
+
+ std::vector<int32_t> lengths(num_values);
+ for (int idx = 0; idx < num_values; idx++) {
+ auto len = static_cast<const int32_t>(src[idx].len);
+ lengths[idx] = len;
+ encoded_size_ += len;
+ }
+ length_encoder_.Put(lengths.data(), num_values);
+ PARQUET_THROW_NOT_OK(sink_.Reserve(encoded_size_));
+
+ for (int idx = 0; idx < num_values; idx++) {
+ sink_.UnsafeAppend(src[idx].ptr, lengths[idx]);
+ }
+}
+
+template <typename DType>
+void DeltaLengthByteArrayEncoder<DType>::PutSpaced(const T* src, int
num_values,
+ const uint8_t* valid_bits,
+ int64_t valid_bits_offset) {
+ if (valid_bits != NULLPTR) {
+ PARQUET_ASSIGN_OR_THROW(auto buffer, ::arrow::AllocateBuffer(num_values *
sizeof(T),
+
this->memory_pool()));
+ T* data = reinterpret_cast<T*>(buffer->mutable_data());
+ int num_valid_values = ::arrow::util::internal::SpacedCompress<T>(
+ src, num_values, valid_bits, valid_bits_offset, data);
+ Put(data, num_valid_values);
+ } else {
+ Put(src, num_values);
+ }
+}
+
+template <typename DType>
+std::shared_ptr<Buffer> DeltaLengthByteArrayEncoder<DType>::FlushValues() {
+ std::shared_ptr<Buffer> encoded_lengths = length_encoder_.FlushValues();
+
+ std::shared_ptr<Buffer> data;
+ PARQUET_THROW_NOT_OK(sink_.Finish(&data));
+ sink_.Reset();
+
+ PARQUET_THROW_NOT_OK(sink_.Append(encoded_lengths->data(),
encoded_lengths->size()));
+ PARQUET_THROW_NOT_OK(sink_.Append(data->mutable_data(), data->size()));
+
+ std::shared_ptr<Buffer> buffer;
+ PARQUET_THROW_NOT_OK(sink_.Finish(&buffer, true));
Review Comment:
remember to clear the `encoded_size_` here
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