1. A method for processing transactions using graph-based computations, the method including: selecting a computation graph from a plurality of computation graphs, including determining which computation graph among the plurality of computation graphs includes one or more graph elements that are associated with a computation to be performed for a given transaction, associating the given transaction with an instance of the selected computation graph, in which the selected computation graph includes computation elements configured to instantiate respective graph elements in the instance of the selected computation graph, and executing the instance of the selected computation graph to perform the computation.