Package org.apache.druid.frame.write

Class FrameWriterUtils

java.lang.Object
org.apache.druid.frame.write.FrameWriterUtils
public class FrameWriterUtils extends Object
Utility methods used by FrameWriter implementations.

  • Field Details

    • NULL_STRING_MARKER

      public static final byte NULL_STRING_MARKER
      See Also:

    • NULL_STRING_MARKER_ARRAY

      public static final byte[] NULL_STRING_MARKER_ARRAY

    • RESERVED_FIELD_PREFIX

      public static final String RESERVED_FIELD_PREFIX
      See Also:

  • Constructor Details

    • FrameWriterUtils

      public FrameWriterUtils()

  • Method Details

    • writeFrameHeader

      public static long writeFrameHeader(org.apache.datasketches.memory.WritableMemory memory, long startPosition, FrameType frameType, long totalSize, int numRows, int numRegions, boolean permuted)
      Writes a frame header to a memory locations.

    • getUtf8ByteBuffersFromStringSelector

      public static List<ByteBuffer> getUtf8ByteBuffersFromStringSelector(DimensionSelector selector, boolean multiValue)
      Retrieves UTF-8 byte buffers from a DimensionSelector, which is expected to be the kind of selector you get for an STRING column. Null strings are returned as NULL_STRING_MARKER_ARRAY.
      Parameters:
      selector - the selector
      multiValue - if true, return an array that corresponds exactly to DimensionSelector.getRow(). if false, always return a single-valued array. In particular, this means [] is returned as [NULL_STRING_MARKER_ARRAY].
      Returns:
      UTF-8 strings. The list itself is never null.

    • getUtf8ByteBuffersFromStringArraySelector

      @Nullable public static List<ByteBuffer> getUtf8ByteBuffersFromStringArraySelector(BaseObjectColumnValueSelector selector)
      Retrieves UTF-8 byte buffers from a ColumnValueSelector, which is expected to be the kind of selector you get for an ARRAY<STRING> column. Null strings are returned as null. If the entire array returned by BaseObjectColumnValueSelector.getObject() is null, returns either null or NULL_STRING_MARKER_ARRAY depending on the value of "useNullArrays".
      Parameters:
      selector - array selector
      Returns:
      UTF-8 strings. The list itself may be null.

    • findDisallowedFieldNames

      public static Set<String> findDisallowedFieldNames(RowSignature signature)
      Checks the provided signature for any disallowed field names. Returns any that are found.

    • verifySortColumns

      public static void verifySortColumns(List<KeyColumn> keyColumns, RowSignature signature)
      Verifies whether the provided sortColumns are all sortable, and are a prefix of the signature. This is required because it allows us to treat the sort key as a chunk of bytes. Exits quietly if the sort columns are OK. Throws an exception if there is a problem.
      Throws:
      IllegalArgumentException - if there is a problem

    • copyByteBufferToMemoryAllowingNullBytes

      public static void copyByteBufferToMemoryAllowingNullBytes(ByteBuffer src, org.apache.datasketches.memory.WritableMemory dst, long dstPosition, int len)
      Copies src to dst without making any modification to the source data.

    • copyByteBufferToMemoryDisallowingNullBytes

      public static int copyByteBufferToMemoryDisallowingNullBytes(ByteBuffer src, org.apache.datasketches.memory.WritableMemory dst, long dstPosition, int len, boolean removeNullBytes)
      Copies src to dst, disallowing null bytes to be written to the destination. If removeNullBytes is true, the method will drop the null bytes, and if it is false, the method will throw an exception. The written bytes can be less than "len" if the null bytes are dropped, and the callers must evaluate the return value to see the actual length of the buffer that is copied

    • replaceUnknownTypesWithNestedColumns

      public static RowSignature replaceUnknownTypesWithNestedColumns(RowSignature rowSignature)