Query Planning for Continuous Aggregation Queries over a Network of Data Aggregators

—Continuous queries are used to monitor changes to time varying data and to provide results useful for online decision making. Typically a user desires to obtain the value of some aggregation function over distributed data items, for example, to know value of portfolio for a client; or the AVG of temperatures sensed by a set of sensors. In these queries a client specifies a coherency requirement as part of the query. We present a low-cost, scalable technique to answer continuous aggregation queries using a network of aggregators of dynamic data items. In such a network of data aggregators, each data aggregator serves a set of data items at specific coherencies. Just as various fragments of a dynamic web-page are served by one or more nodes of a content distribution network, our technique involves decomposing a client query into sub-queries and executing sub-queries on judiciously chosen data aggregators with their individual sub-query incoherency bounds. We provide a technique for ge...

• Type: Journal
• Year: 2012
• Where: TKDE
• Authors: Rajeev Gupta, Krithi Ramamritham
• Keywords: Aggregators, Content Distribution Network, Dynamic Data, Formal Methods, TKDE 2012