A dynamic signature technique for multimedia databases

Abstract

A signature file acts as a filtering mechanism to reduce the amount of data that needs to be searched during query evaluation. Even though several techniques for organizing and searching signature files have been proposed in literature, they have serious limitations when applied to multimedia databases, where integrated access methods to text and image content are needed. A new signature technique, called Quick Filter, is proposed in the paper. According to this technique, signatures are divided into partitions, each of which holds signatures sharing the same characteristic key. As a result, it is possible to determine if the signatures in a partition satisfy a query by merely examining the key. Partitions not matching the key need not be searched. This method is based on dynamic hashing since signatures are hashed into partitions according to the keys and the file size, computed algorithmically from the signatures. Implementation of this technique is illustrated using an example and is verified by analytical performance evaluation. The result is a signature technique which satisfies the requirements for access methods in multimedia databases: dynamicity, with respect to insertions and updates, good query processing performance on large databases for high-weight queries.