Filtered Indices and Their Use in Flexible Schema Scenarios

Efficient and convenient handling of heterogeneous data is a current challenge for data management systems. In this paper, we discuss several common relational approaches to represent heterogeneity and argue for a design based on a single wide-table, referred to as a flexible schema. For this scenario, we focus on partial indexation and its support for efficient data storage and processing. Filtered indices provide partial indexation functionality in the Microsoft SQL Server product. We describe here the implementation of this feature, including index utilization in queries, index maintenance and query parameterization issues. Our performance experiments validate the expected benefits of the approach in our implementation.