International Journal of Modern Engineering Research (IJMER)
Decision making can be regarded as the reflective development consequential in the selection of a course of action among several alternative scenarios. Continuous and uninterrupted aggregation queries are used to monitor the changes in data with time varying for online decision making. Usually a user requirements to obtain the value of some aggregation function larger than distributed data items, for example, to be familiar with value of portfolio for a client; or the average of temperatures sensed by a set of sensors. In these queries a client identifies a coherency requirement as measurement of the query.