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Control-based Quality Adaptation in Data Stream Management Systems (DSMS)

Control-based Quality Adaptation in Data Stream Management Systems (DSMS). Data Stream Management System (DSMS). Continuous data, discarded after being processed Continuously answers queries Applications Financial analysis Mobile services Sensor networks Network monitoring More ….

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Control-based Quality Adaptation in Data Stream Management Systems (DSMS)

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  1. Control-based Quality Adaptation in Data Stream Management Systems (DSMS)

  2. Data Stream Management System (DSMS) • Continuous data, discarded after being processed • Continuously answers queries • Applications • Financial analysis • Mobile services • Sensor networks • Network monitoring • More …

  3. DSMS architecture • Network of query operators (1 – 12) • Each operator has its own queue • Scheduler decides which operator to execute • Query results pushed to clients • For our purposes, DSMS can be viewed as a blackbox

  4. Load Shedding • Eliminating excessive load by dropping data items  less QoS violations • Basic algorithm (Tatbul et al., 2003): • Key questions • When? • How much? • Where?

  5. What’s missing? • Current solutions focus on steady-state performance • Open-loop control ? • Assuming there inputs reach steady states • However, arrivals are bursty in practice – always in transient state • The solution: closed-loop control

  6. Why Closed-Loop Control • Reduce the effects of modeling error, input and output disturbances • Improve dynamic response • Stabilize unstable systems

  7. Identification of Database System

  8. Control of Database System • Output is delay time • Incoming flow rate fluctuates and unknown • Uncertainties in cost factor

  9. Experiments • Implemented a controller in a real DSMS – Borealis • With bursty synthetic and real data

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