Data summarization

A database management system provides the capability to perform cluster analysis and provides improved performance in model building and data mining, good integration with the various databases throughout the enterprise, and flexible specification and adjustment of the models being built, but which provides data mining functionality that is accessible to users having limited data mining expertise and which provides reductions in development times and costs for data mining projects. A database management system for in-database clustering comprises a first data table and a second data table, each data table including a plurality of rows of data, means for building a clustering model using the first data table using a portion of the first data table, wherein the portion of the first data table is selected by partitioning, density summarization, or active sampling of the first data table, and means for applying the clustering model using the second data table to generate apply output data.