1. A system, comprising: multiple computer servers programmed to perform operations comprising: dividing a directed graph representing web resources and links into shards, each shard comprising a respective portion of the graph representing multiple web resources and links associated with the multiple web resources; assigning each of the shards to a respective server, including assigning, to each of the respective servers, data describing the links associated with the multiple web resources represented by the portion of the graph corresponding to the shard assigned to the server; and calculating, in parallel, a distance table for each of the web resources in each shard using a nearest seed computation in the server to which the shard was assigned using the data describing the links associated with the multiple web resources.