MG4J (Managing Gigabytes for Java) is a collaborative effort aimed at providing a free Java implementation of inverted-index compression techniques; as a by-product, it offers several general-purpose optimised classes, including fast and compact mutable strings, bit-level I/O, fast unsynchronised buffered streams, (possibly signed) minimal perfect hashing, etc. MG4J functions as a full-fledged text-indexing system. It can analyze, index, and query consistently large document collections.


This release has a new, high-performance index format, several optimizations, indices with arbitrary payloads (dates, integers, etc.), faster minimal perfect hashing, new operators, and better algorithms.

URL: MG4J: Managing Gigabytes for Java™