Updating an Existing Social Graph Snapshot via a Limited API

We study the problem of graph tracking with limited information. In this paper, we focus on updating a social graph snapshot. Say we have an existing partial snapshot, G1, of the social graph stored at some system. Over time G1 becomes out of date. We want to update G1 through a public API to the actualy graph, restricted by the number of API calls allowed. Periodically recrawling every node in the snapshot is prohibitively expensive. We propose a scheme where we exploit indegrees and outdegrees to discover changes to the actual graph. When there is ambiguity, we probe the graph and verify edges. We propose a novel strategy designed for limited information that can be adapted to different levels of staleness. We evaluate our strategy against recrawling on real datasets and show that it saves an order of magnitude of API calls while introducing minimal errors.