1. A method comprising: generating, in a query pre-processor, a set of pre-computed materialized sub-graphs from a dataset by: grouping all terms in said dataset; and for each group, executing a dynamic random-walk based search over the full dataset using terms in said group as random walk starting points; based on said executing, identifying important nodes; and using said nodes to construct a corresponding sub-graph; receiving a search query having at least one search query term; accessing a particular one of said constructed corresponding sub-graphs; executing a dynamic authority-based keyword search on said particular accessed sub-graph; retrieving nodes in said dataset based on said executing; and responding to said search query with results including said retrieved nodes.