1. A method for building an index, comprising: storing, using a computer with a processor, a current version of a store having a tokenized version of each document in a corpus of documents, a delta store accumulating changes to the current version of the store, and previously generated global analysis computations, wherein the previously generated global analysis computations include an anchor text table, a rank table, and a duplicates table; building a new version of the index and outputting a raw anchor text table and a raw duplicates table a by accessing the current version of the store, the delta store, and the previously generated global analysis, computations; and generating new global analysis computations by accessing the raw anchor text table, the raw duplicates table, and the previously generated global analysis computations, wherein the new global analysis computations include a new anchor text table, a new rank table, and a new duplicates table.