private void preprocessSearchKey(Pair<byte[], byte[]> p) {
    if (!UNSAFE_UNALIGNED) {
      // do nothing
      return;
    }
    byte[] key = p.getFirst();
    byte[] mask = p.getSecond();
    for (int i = 0; i < mask.length; i++) {
      // set non-fixed part of a search key to 0.
      if (mask[i] == 2) {
        key[i] = 0;
      }
    }
  }
Row tracker (keeps all next rows after SEEK_NEXT_USING_HINT was returned)
hbase-client/src/main/java/org/apache/hadoop/hbase/filter/FuzzyRowFilter.java