A data warehouse collects and maintains integrated information from heterogeneous data sources for OLAP and decision support. An important task in data warehouse design is the selection of views to materialize, in order to minimize the response time and maintenance cost of generalized project-select-join (GPSJ) queries. We discuss how to construct GPSJ view graphs. GPSJ view graphs are directed acyclic graphs, used to compactly encode and represent different possible ways of evaluating a set of GPSJ queries. Our view graph construction algorithm, GPSJVIEWGRAPHBUILDER, incrementally constructs GPSJ view graphs based on a set of merge rules. We provide a set of merging rules to construct GPSJ view graphs in the presence of duplicate sensitive and insensitive aggregates. The merging algorithm used in GPSJVIEWGRAPH-BUILDER ensures that each node is correctly added to the view graph, and employs the merge rules to ensure that relationships between nodes from different queries are incorporated into the view graph
