Method getRowKeyRegex

src/search/TimeSeriesLookup.java:441–548

Constructs a row key regular expression to pass to HBase if the user gave some tags in the query @return The regular expression to use.

()

   * @return The regular expression to use.
   */
  private String getRowKeyRegex() {
    final StringBuilder tagv_buffer = new StringBuilder();
    // remember, tagks are sorted in the row key so we need to supply a sorted
    // regex or matching will fail.
    Collections.sort(pairs);
    
    final short name_width = TSDB.tagk_width();
    final short value_width = TSDB.tagv_width();
    final short tagsize = (short) (name_width + value_width);
    
    int index = 0;
    final StringBuilder buf = new StringBuilder(
        22  // "^.{N}" + "(?:.{M})*" + "$" + wiggle
        + ((13 + tagsize) // "(?:.{M})*\\Q" + tagsize bytes + "\\E"
           * (pairs.size())));
    buf.append("(?s)^.{").append(query.useMeta() ? TSDB.metrics_width() : 
      TSDB.metrics_width() + Const.SALT_WIDTH())
      .append("}");
    if (!query.useMeta()) {
      buf.append("(?:.{").append(Const.TIMESTAMP_BYTES).append("})*");
    }
    buf.append("(?:.{").append(tagsize).append("})*");
    
    // at the top of the list will be the null=tagv pairs. We want to compile
    // a separate regex for them.
    for (; index < pairs.size(); index++) {
      if (pairs.get(index).getKey() != null) {
        break;
      }
      
      if (index > 0) {
        buf.append("|");
      }
      buf.append("(?:.{").append(name_width).append("})");
      buf.append("\\Q");
      QueryUtil.addId(buf, pairs.get(index).getValue(), true);
    }
    buf.append("(?:.{").append(tagsize).append("})*")
       .append("$");
    
    if (index > 0 && index < pairs.size()) {
      // we had one or more tagvs to lookup AND we have tagk or tag pairs to
      // filter on, so we dump the previous regex into the tagv_filter and
      // continue on with a row key
      tagv_buffer.append(buf.toString());
      LOG.debug("Setting tagv filter: " + QueryUtil.byteRegexToString(buf.toString()));
    } else if (index >= pairs.size()) {
      // in this case we don't have any tagks to deal with so we can just
      // pass the previously compiled regex to the rowkey filter of the 
      // scanner
      LOG.debug("Setting scanner row key filter with tagvs only: " + 
          QueryUtil.byteRegexToString(buf.toString()));
      if (tagv_buffer.length() > 0) {
        tagv_filter = tagv_buffer.toString();
      }
      return buf.toString();
    }