1. SWiM Panel on Engine Implementation Jennifer Widom

2. Query Processing Architecture Input Data Streams Users issue continuous and ad-hoc queries Administrator can monitor query execution and adjust run-time parameters Applications register continuous queries Output Stream   X X Waiting Op Ready Op Running Op Synopses Query Plans Scheduler

3. Issues Memory versus disk for intermediate state More generally: More generally: Is there a clear latency-accuracy-storage tradeoff? What is the objective of the scheduler? More generally: More generally: What are the performance metrics for continuous queries?

4. Issues (cont’d) How important is a built-in approach to approximation? More generally: More generally: Will data streams really be all that fast? If so, can’t we expect the source to filter? How adaptive does execution really need to be? More generally: More generally: Will data streams really be all that variable?

5. Issues (cont’d) What does the API for a Data Stream Management System look like? –For registering queries –For seeing results –For understanding approximation –For monitoring the system