1. A method comprising: collecting, by one or more computing devices, a plurality of information items of a plurality of types relevant to a user, wherein: the information items are collected from at least one social-networking system and at least one third-party system; and the user is a member of the at least one social-networking system; determining, by one or more computing devices, a relevance value for each of the information items, wherein the relevance value is based at least in part on: how close a time associated with the information item is to a current time; and how close a node representing the information item is to a node representing the user in a graph associated with the social-networking system, the graph representing information contained in the social-networking system; classifying, by one or more computing devices, one or more of the information items as being non-deterministic based at least in part on each of the non-deterministic information items having a relevance value that decreases with time; classifying, by one or more computing devices, one or more other ones of the information items as being deterministic based at least in part on each of the deterministic information items having a relevance value that remains substantially constant over time; sending, by one or more computing devices, one or more push notifications to one or more client devices associated with the user, the push notifications comprising one or more of the non-deterministic information items sent in an order of their respective relevance values; and storing, by one or more computing devices, the deterministic information items for later retrieval by the user.