Abstract: Preferred indexes for a relational database are identified. Queries from users are received and a sample of user queries are analysed to identify candidate indexes. Index permutations are identified by processing the candidate indexes in combinations identified from the sample of user queries. A preferred index set is identified by comparing the performance of the index permutations.

Abstract: A configurable circuit having a plurality of functioning devices and reconfigurable connections is reconfigured. Initial designs for configurations of the circuit are generated. Then, the following steps are repeatedly performed. Firstly, routing data for the designs is generated. Secondly, circuit designs are tested by measuring an indication of the required function. Thirdly, preferred designs are selected and finally next designs are generated from the preferred designs.