@Override
  public void afterIndexLookup(Collection results) {
    if (results == null) {
      // according to javadocs in QueryObserver, can be null if there
      // is an exception
      return;
    }

    // append the size of the lookup results (and bucket id if its an Index on bucket)
    // to IndexInfo results Map.
    Map indexMap = (Map) indexInfo.get();
    Index index = (Index) lastIndexUsed.get();
    if (index != null) {
      IndexInfo indexInfo = (IndexInfo) indexMap.get(getIndexName(index, lastKeyUsed.get()));
      if (indexInfo != null) {
        indexInfo.getResults().put(index.getRegion().getFullPath(), results.size());
      }
    }
    lastIndexUsed.set(null);
    lastKeyUsed.set(null);
    if (th != null) {
      th.hook(3);
    }
  }
appends the size of the lookup to the last index name in the list
geode-core/src/main/java/org/apache/geode/cache/query/internal/IndexTrackingQueryObserver.java