PIVOT and UNPIVOT: Optimization and Execution Strategies in an RDBMS

(Conor Cunningham, Csar A. Galindo-Legaria and Goetz Graefe) PIVOT and UNPIVOT, two operators on tabular data that exchange rows and columns,
enable data transformations useful in data
modeling, data analysis, and data presentation.
They can quite easily be implemented inside a
query processor, much like select, project, and
join. Such a design provides opportunities for
better performance, both during query
optimization and query execution. We discuss
query optimization and execution implications of
this integrated design and evaluate the
performance of this approach using a prototype
implementation in Microsoft SQL Server.