A tool to sort index according to a float document weight. Documents with high weight are given low document numbers, which means that they will be first evaluated. When using a strategy of "early termination" of queries (see TimeLimitedCollector) such sorting significantly improves the quality of partial results.
(Originally this tool was created by Doug Cutting in Nutch, and used norms as document weights - thus the ordering was limited by the limited resolution of norms. This is a pure Lucene version of the tool, and it uses arbitrary floats from a specified stored field).