if (indexesUsedByStreams == null)
{
indexesUsedByStreams = new LinkedHashMap<HistoricalStreamIndexDesc, List<Integer>>();
for (int pollingStream : pollingStreams)
{
QueryGraphValue queryGraphValue = queryGraph.getGraphValue(pollingStream, historicalStreamNum);
QueryGraphValuePairHashKeyIndex hashKeyProps = queryGraphValue.getHashKeyProps();
String[] indexProperties = hashKeyProps.getIndexed();
Class[] keyTypes = getPropertyTypes(hashKeyProps.getKeys());
Class[] indexTypes = getPropertyTypes(typesPerStream[historicalStreamNum], indexProperties);