A database system may include a database, a set of tools for accessing the database, a data buffer for storing data objects from the database, and a "delta buffer" for storing delta records. Simulations may be performed in the database system by the set of tools that access the database. Simulative changes of the data may be handled by the delta buffer. The delta buffer need not contain all the data used for simulations and may include delta records. Each delta record may include simulative changes of the data and a request identifier. The content of the delta buffer may be integrated with the unchanged, original data from the database. The delta buffer in combination with the data buffer may provide an integrated view for tools that access the database, such as planning and reporting tools.