public boolean isEqual(byte[] left, int leftOffset, Position readPos, int length) {
    return isEqual(left, leftOffset, readPos.bufferIndex, readPos.offset, length);
  }
Compares the current readPosition of the buffer with the external byte array.
Does not modify readPoint.
serde/src/java/org/apache/hadoop/hive/serde2/WriteBuffers.java