6. The method of claim 1 , further comprising: accessing a social graph comprising a plurality of nodes and a plurality of edges connecting the nodes, each of the edges between two of the nodes representing a single degree of separation between them, the nodes comprising: a plurality of user nodes corresponding to a plurality of users of the online social network, respectively; and a plurality of concept nodes corresponding to a plurality of concepts associated with the online social network, respectively; wherein each query in the first set of queries corresponds to a particular user node, and each retrieved object corresponds to a user node or concept node of the plurality of nodes.
6. The method of claim 1 , further comprising: accessing a social graph comprising a plurality of nodes and a plurality of edges connecting the nodes, each of the edges between two of the nodes representing a single degree of separation between them, the nodes comprising: a plurality of user nodes corresponding to a plurality of users of the online social network, respectively; and a plurality of concept nodes corresponding to a plurality of concepts associated with the online social network, respectively; wherein each query in the first set of queries corresponds to a particular user node, and each retrieved object corresponds to a user node or concept node of the plurality of nodes. 8. The method of claim 6 , wherein each query constraint is for one or more nodes of the plurality of nodes connected to a first of the selected nodes by a first of the selected edges.