PROCESSING TIME-CONSTRAINED AGGREGATE QUERIES IN CASE-DB

In this paper, we present an algorithm to strictly control the time to process an estimator for an aggregate relational query. The algorithm implemented in a prototype database management system, called CASE-DB , iteratively samples from input relations, and evaluates the associat ed estimator until the time quota expires. In order to estimate the ti me cost of a query, CASE-DB uses adaptive time cost formulas. The form ulas are adaptive in that the parameters of the formulas can be aduste d at run time to better fit the characteristics of a query. To control the use of time quota, CASE-DB adopts the one-at-a-time-interval time control strategy to make a tradeoff between the risks of overspending and the overhead. finally, experimental evaluation of the methodology is presented.