1. A method in a computing system for analyzing user behavior information, comprising: receiving a stream of user behavior information; augmenting a representation of user behavior in accordance with the received stream of user behavior information, the representation comprising a sparse matrix of elements, each element containing information indicating a user behavior fact, wherein a recurring time period is indicated in connection with the representation, wherein each element of the sparse matrix identifies an instance of the recurring time period to which the user behavior fact indicated by the information contained by the element relates, and wherein each element of the sparse matrix indicates a number of times a particular user performed an action of a particular type during the identified instance of the recurring time period; and analyzing the sparse matrix to obtain an analysis result for the stream of user behavior.