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We present a shape deenition language, called SDL, for retrieving objects based on shapes contained in the histories associated with these objects. It is a small, yet powerful, language that allows a rich v ariety of queries about the shapes found in historical time sequences. An interesting feature of SDLis its ability to perform blurry matching. A blurry"(More)
In this article, we describe our approach to the compile-time optimization and parallelization of queries for execution in DBS3 or EDS. DBS3 is a shared-memory parallel database system, while the EDS system has a distributed-memory architecture. Because DBS3 implements a parallel dataflow execution model, this approach applies to both architectures. Using(More)
The co.91 of query optimization is ufiected by both the ~eurch apocc und the search atmlegy of the opti,aizer. I~I (1 pumllel ecectrlion environment, Ihe search ap~cc tends lo he much lurger than in the centmlized ca,sc-. This is due to the high number of ezecution okeruutivrs which implies a aignijiconl increase in the op~imisutiofc coal. 118 &a puper, we(More)
Complex database queries require the use of memory-intensive operators like sort and hash-join. Those operators need memory, also referred to as SQL memory, to process their input data. For example, a sort operator uses a work area to perform the in-memory sort of a set of rows. The amount of memory allocated by these operators greatly affects their(More)
In this paper, we present a new algorithm for estimating the size of equality join of multiple database tables. The proposed algorithm, Correlated Sampling, constructs a small space synopsis for each table, which can then be used to provide a quick estimate of the join size of this table with other tables subject to dynamically specified predicate filter(More)
Object-oriented data models are being extended with recursion to gain expressive power. This complicates the optimization problem which has to deal with recursive queries on complex objects. Because unary operations invoking methods or path expressions on objects may be costly to execute, traditional heuristics for optimizing recursive queries are no longer(More)
In the industrial context of the EDS project, we have designed and implemented a query optimizer which we have integrated within a parallel database system. The optimizer takes as input a query expressed in ESQL, an extension of SQL with objects and rules, and produces a minimum cost parallel execution plan. Our research agenda has focused on several(More)