Module org.apache.arrow.dataset
Package org.apache.arrow.dataset.scanner

Class ArrowScannerReader

java.lang.Object
org.apache.arrow.vector.ipc.ArrowReader
org.apache.arrow.dataset.scanner.ArrowScannerReader
All Implemented Interfaces:
AutoCloseable, DictionaryProvider
public class ArrowScannerReader extends ArrowReader
An implementation of ArrowReader that reads the dataset from Scanner.

  • Constructor Details

    • ArrowScannerReader

      public ArrowScannerReader(Scanner scanner, BufferAllocator allocator)
      Constructs a scanner reader using a Scanner.
      Parameters:
      scanner - scanning data over dataset
      allocator - to allocate new buffers

  • Method Details

    • loadRecordBatch

      protected void loadRecordBatch(ArrowRecordBatch batch)
      Description copied from class: ArrowReader
      Load an ArrowRecordBatch to the readers VectorSchemaRoot.
      Overrides:
      loadRecordBatch in class ArrowReader
      Parameters:
      batch - the record batch to load

    • loadDictionary

      protected void loadDictionary(ArrowDictionaryBatch dictionaryBatch)
      Description copied from class: ArrowReader
      Load an ArrowDictionaryBatch to the readers dictionary vectors.
      Overrides:
      loadDictionary in class ArrowReader
      Parameters:
      dictionaryBatch - dictionary batch to load

    • loadNextBatch

      public boolean loadNextBatch() throws IOException
      Description copied from class: ArrowReader
      Load the next ArrowRecordBatch to the vector schema root if available.
      Specified by:
      loadNextBatch in class ArrowReader
      Returns:
      true if a batch was read, false on EOS
      Throws:
      IOException - on error

    • bytesRead

      public long bytesRead()
      Description copied from class: ArrowReader
      Return the number of bytes read from the ReadChannel.
      Specified by:
      bytesRead in class ArrowReader
      Returns:
      number of bytes read

    • closeReadSource

      protected void closeReadSource() throws IOException
      Description copied from class: ArrowReader
      Close the underlying read source.
      Specified by:
      closeReadSource in class ArrowReader
      Throws:
      IOException - on error

    • readSchema

      protected Schema readSchema() throws IOException
      Description copied from class: ArrowReader
      Read the Schema from the source, will be invoked at the beginning the initialization.
      Specified by:
      readSchema in class ArrowReader
      Returns:
      the read Schema
      Throws:
      IOException - on error