1. A method comprising: receiving, by a database server from a remote application server, a multi-part query specifying or associated with a calculation scenario defining a data flow model that includes a plurality of calculation nodes, the plurality of calculation nodes comprising a main section of nodes and two or more branches of nodes, each calculation node defining one or more operations to execute on the database server; instantiating, by the database server, the specified calculation scenario; executing, by the database server, the operations defined by the calculation nodes of the main section of the instantiated calculation scenario a single time and executing the operations defined by the calculation nodes of the branches to result in respective responsive data sets corresponding to each branch, wherein at least a portion of the main section is reused by at least one of the branches; and providing, by the database server to the application server, the responsive data sets; wherein an input for each calculation node comprises one or more of: a physical table, a join view, an OLAP view, and another calculation node.