Method computeUnion

src/query/expression/UnionIterator.java:171–201

Computes the union of all sets, matching on tags and optionally the aggregated tags across each variable.

()

   * aggregated tags across each variable.
   */
  private void computeUnion() {
    // key = flattened tags, array of queries.size()
    final ByteMap<ExpressionDataPoint[]> ordered_union = 
        new ByteMap<ExpressionDataPoint[]>(); 

    final Iterator<ITimeSyncedIterator> it = queries.values().iterator();
    while (it.hasNext()) {
      final ITimeSyncedIterator sub = it.next();
      final ExpressionDataPoint[] dps = sub.values();
      final ByteMap<Integer> local_tags = new ByteMap<Integer>();
      
      for (int i = 0; i < sub.size(); i++) {
        final byte[] key = flattenTags(union_on_query_tagks, include_agg_tags, 
            dps[i], sub);
        local_tags.put(key, i);
        ExpressionDataPoint[] udps = ordered_union.get(key);
        if (udps == null) {
          udps = new ExpressionDataPoint[queries.size()];
          ordered_union.put(key, udps);
        }
        udps[sub.getIndex()] = dps[i];
      }
    }
    
    if (ordered_union.size() < 1) {
      // if no data, just stop here
      return;
    }
    
    setCurrentAndMeta(ordered_union);
  }
  
  /**
   * Takes the resulting union and builds the {@link #current_values}