Method setDataTableScanFilter

src/query/QueryUtil.java:414–494

Sets a filter or filter list on the scanner based on whether or not the query had tags it needed to match. NOTE: This method will sort the group bys. @param scanner The scanner to modify. @param group_bys An optional list of tag keys that we want to group on. May be null. @param row_key_literals An

(
      final Scanner scanner, 
      final List<byte[]> group_bys, 
      final ByteMap<byte[][]> row_key_literals,
      final boolean explicit_tags,
      final boolean enable_fuzzy_filter,
      final int end_time)

   * to stop scanning.
   */
  public static void setDataTableScanFilter(
      final Scanner scanner, 
      final List<byte[]> group_bys, 
      final ByteMap<byte[][]> row_key_literals,
      final boolean explicit_tags,
      final boolean enable_fuzzy_filter,
      final int end_time) {
    
    // no-op
    if ((group_bys == null || group_bys.isEmpty()) 
        && (row_key_literals == null || row_key_literals.isEmpty())) {
      return;
    }
    
    if (group_bys != null) {
      Collections.sort(group_bys, Bytes.MEMCMP);
    }
    
    final int prefix_width = Const.SALT_WIDTH() + TSDB.metrics_width() + 
        Const.TIMESTAMP_BYTES;
    
    final FuzzyRowFilter fuzzy_filter;
    if (explicit_tags && 
        enable_fuzzy_filter && 
        row_key_literals != null && 
        !row_key_literals.isEmpty()) {
      
      final byte[] fuzzy_key = new byte[prefix_width + (row_key_literals.size() * 
          (TSDB.tagk_width() + TSDB.tagv_width()))];
      System.arraycopy(scanner.getCurrentKey(), 0, fuzzy_key, 0, 
          scanner.getCurrentKey().length);
      
      final List<FuzzyFilterPair> fuzzy_filter_pairs = 
          buildFuzzyFilters(row_key_literals, fuzzy_key);
      
      // The Fuzzy Filter list is sorted: the first and last filters row key
      // can be used to build the stop key for the scanner
      final byte[] stop_key = Arrays.copyOf(
          fuzzy_filter_pairs.get(fuzzy_filter_pairs.size() - 1).getRowKey(),
          fuzzy_key.length);
      System.arraycopy(scanner.getCurrentKey(), 0, stop_key, 0, prefix_width);
      Internal.setBaseTime(stop_key, end_time);
      int idx = prefix_width + TSDB.tagk_width();
      // max out the tag values
      while (idx < stop_key.length) {
        for (int i = 0; i < TSDB.tagv_width(); i++) {
          stop_key[idx++] = (byte) 0xFF;
        }
        idx += TSDB.tagk_width();
      }

      scanner.setStartKey(fuzzy_key);
      scanner.setStopKey(stop_key);
      fuzzy_filter = new FuzzyRowFilter(fuzzy_filter_pairs);
    } else {
      fuzzy_filter = null;
    }