BlackRay is a relational database system designed to offer performance features commonly associated with search engines. It offers SQL support and sophisticated operational and management features. Load-balancing and operational stability by means of N+1 redundance are included. BlackRay is called a "Data Engine" since it combines traditional, relational database features and SQL with the power and flexibility of search engines. It is a true hybrid, offering transaction support, data-versioned snapshots, and sophisticated function-based indices. Wildcards, phonetic, and fuzzy logic searches are supported, as well. BlackRay supports a subset of the SQL92 standard and provides JDBC/ODBC/native driver options via the PostgreSQL protocol, in addition to an API based query option. The project is released under the GPLv2, with some drivers available under BSD-style licenses. Commercial support contracts are available as well.
RestPose is a search engine. It is designed to take a set of documents and then, when given a query, to return ranked lists of documents which are a good match for that query. RestPose manages a set of internal indexes and provides an interface (over HTTP, in a fairly RESTful style, using JSON as the main transfer format) which allows documents to be submitted and removed from indexes, and which allows searches to be performed.
Libcolumbus is a small error tolerant search engine designed to deal with noisy data and typos. It will power the searches in the next generation of Ubuntu's HUD system as well as other searches. It has a fast implementation of the Levenshtein distance algorithm, which allows it to correct errors such as added and dropped letters (e.g. 'bar' -> 'bard'), changed letters ('ctr' -> 'car') and translations ('acr' -> 'car'). It also allows the user to customize the error values. Libcolumbus is designed to be small, efficient and easy to embed. It is programmed in C++ but also provides C and Python APIs.