Method UnionIterator

src/query/expression/UnionIterator.java:90–127

Default ctor @param id The variable ID for this iterator @param results Upstream iterators @param union_on_query_tagks Whether or not to flatten and join on only the tags from the query or those returned in the results. @param include_agg_tags Whether or not to include the flattened aggregated tag k

(final String id, final Map<String, ITimeSyncedIterator> results,
      final boolean union_on_query_tagks, final boolean include_agg_tags)

   * tag keys in the join.
   */
  public UnionIterator(final String id, final Map<String, ITimeSyncedIterator> results,
      final boolean union_on_query_tagks, final boolean include_agg_tags) {
    this.id = id;
    this.union_on_query_tagks = union_on_query_tagks;
    this.include_agg_tags = include_agg_tags;
    timestamp = Long.MAX_VALUE;
    queries = new HashMap<String, ITimeSyncedIterator>(results.size());
    current_values = new HashMap<String, ExpressionDataPoint[]>(results.size());
    single_series_matrix = new HashMap<String, int[]>(results.size());
    index_to_names = new String[results.size()];
    fill_policy = new NumericFillPolicy(FillPolicy.ZERO);
    fill_dp = new ExpressionDataPoint();
    
    int i = 0;
    for (final Map.Entry<String, ITimeSyncedIterator> entry : results.entrySet()) {
      if (LOG.isDebugEnabled()) {
        LOG.debug("Adding iterator " + entry.getValue());
      }
      queries.put(entry.getKey(), entry.getValue());
      entry.getValue().setIndex(i);
      index_to_names[i] = entry.getKey();
      ++i;
    }

    computeUnion();
    
    // calculate the starting timestamp from the various iterators
    for (final ITimeSyncedIterator it : queries.values()) {
      final long ts = it.nextTimestamp();
      if (ts < timestamp) {
        timestamp = ts;
      }
    }
    
    if (LOG.isDebugEnabled()) {
      LOG.debug("Computed union: " + this);
    }
  }
  
  /**
   * Private copy constructor that copies references and sets up new collections