1. A method for processing data, comprising: obtaining a graph of a social network, wherein the graph comprises: a set of nodes representing users in the social network; and a set of edges representing relationships between pairs of the users; storing, on a single computer system instead of a cluster-based query-processing system that includes multiple computers, a static representation of the graph, wherein the static representation comprises: a first set of fixed-size blocks representing the nodes and the edges; and a first index that maps a set of identifiers for the nodes and the edges to offsets of the first set of fixed-size blocks; identifying, from a stream of events associated with activity in the social network, updates to the graph that occurred subsequent to creation of the static representation; storing, in a memory of the single computer system, a dynamic representation of the identified changes to the graph, wherein the dynamic representation comprises: a second set of fixed-size blocks representing changes to the nodes and edges caused by the updates to the graph; and a second index that maps a subset of the identifiers for the nodes and the edges to offsets of the second set of fixed-size blocks; and using the dynamic representation and the static representation of the graph to process, by the single computer system, one or more queries of the graph by, for each of one or more identifiers in the query: using the second index to match the identifier to an offset to one or more blocks in the second set of fixed-size blocks that match the query; and when the second index does not contain the identifier, using the first index to match the identifier to an offset to one or more blocks in the first set of fixed-size blocks that match the query.