1. A method comprising: by one or more computing devices, receiving a search query requesting one or more first search results of a first object type that corresponds to a user in a social-networking system, the search query comprising an inner query identifying a specified user and requesting one or more second search results of a second object type that corresponds to a concept in the social-networking system; by one or more computing devices, accessing an inverted index of a data store corresponding to the second object type, wherein the inverted index maps a user node to one or more concept nodes in accordance with a second relationship; by one or more computing devices, retrieving the one or more second search results requested by the inner query using the inverted index of the data store corresponding to the second object type, wherein the one or more second search results comprise one or more concept nodes of a social graph in the social-networking system, and the one or more concept nodes are related to the specified user by the second relationship; by one or more computing devices, accessing a forward index of the data store corresponding to the second object type, wherein the forward index maps a concept node to one or more user nodes in accordance with a first relationship; and by one or more computing devices, retrieving the one or more first search results requested by the search query using the second search results and the forward index of the data store corresponding to the second object type, wherein the one or more first search results comprise one or more user nodes of the social graph that are related to the one or more resulting concept nodes by the first relationship.