Optimizing In-Order Execution of Continuous Queries over Streamed Sensor Data
Date
2004-12-20
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Abstract
The widespread use of sensor networks in scientific and
engineering applications leads to increased demand on the
efficient computation of the collected sensor data. Recent
research in sensor and stream data systems adopts the notion
of sliding windows to process continuous queries over
infinite sensor readings. Ordered processing of input data is
essential during query execution for many application scenarios.
In this paper we present three approaches for ordered
execution of continuous sliding window queries over
sensor data. The first approach enforces ordered processing
at the input side of the query execution plan. In the second
approach we utilize the advantage of out-of-order execution
to optimize query operators and enforce an ordered
release of the output results. The third approach is adaptive
and switches between the first and second approaches
to achieve the best overall performance with current input
arrival rates and level of multiprogramming. We study the
performance of the proposed approaches both analytically
and experimentally and under a variety of conditions such
as the asynchronous arrival of input data, and various levels
of multiprogramming. Our performance study is based
on an extensive set of experiments using a realization of the
proposed approaches in a prototype stream query processing
system.
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Computer Science