1. A system comprising: a database; and a cache layer comprising one or more cache clusters, each of the one or more cache clusters operative to: maintain, in a memory of one or more cache nodes of the cache cluster, at least a portion of a social graph, the social graph comprising a plurality of nodes and a plurality of edges connecting the nodes, each node being uniquely identified by a node identifier, and each edge indicating associations between nodes; process one or more queries received from one or more client systems of users of a social network environment, the processing of each query comprising: if the query is for associations between nodes in the portion of the social graph stored in the cache cluster, then respond to the query by searching the portion of the social graph stored in the memory of the cache cluster; and if the query is not for associations between nodes in the portion of the social graph stored in the cache cluster, then forward the query to the database for processing; and send, to the one or more client systems for display, search results responsive to the received queries.