Index-Selection for Minimizing Costs of a NoSQL Cloud Database

Abstract

The index-selection problem in database systems is that of determining a set of indexes (data-access paths) that minimizes the costs of database operations. Although this problem has received significant attention in the context of relational database systems, the established methods and tools do not translate easily to the context of modern non-relational database systems (so-called NoSQL systems) that are widely used in cloud and grid computing, and in particular systems such as DynamoDB from Amazon Web Services. Although the index-selection problem in these contexts appears simple at first glance, due to the very limited indexing features, this simplicity is deceptive because the non-relational nature of these databases and indexes permits more complex indexing schemes to be expressed. This paper motivates and describes the index-selection problem for NoSQL databases, and DynamoDB in particular. It motivates and outlines a cost model to capture the specific monetary costs associated with database operations in this context. The cost model has not only been carefully checked for consistency using the system documentation but also been verified using actual usage costs in a live DynamoDB instance.