Odysseus has some features to measure the latency of single stream elements. This latency information is modeled as an interval. An operator in Odysseus can modify the start point of this interval. This operator sets the endpoint and determines the place in the query plan, where the latency measurement takes place. There can be multiple operators in the plan, to measure latency at different places.
To use this operator you have to set "
#METADATA Latency" in the query.
Important: If you are using operators like Join, you additionally need to add
measurementPoint(String): If you want to use multipe measurements inside a query you could use this parameter to add additional measurement points. This points will contain the current time stamp in nanoseconds, so the difference between the latency start and this value is the latency, measured at this point.