Sphinx - Free open-source SQL full-text search engine
"Sphinx is a full-text search engine, distributed under GPL version 2. [...] Generally, it's a standalone search engine, meant to provide fast, size-efficient and relevant fulltext search functions to other applications. Sphinx was specially designed to integrate well with SQL databases and scripting languages. Currently built-in data source drivers support fetching data either via direct connection to MySQL, PostgreSQL, or from a pipe in a custom XML format.
Sphinx features
- high indexing speed (upto 10 MB/sec on modern CPUs);
- high search speed (avg query is under 0.1 sec on 2-4 GB text collections);
- high scalability (upto 100 GB of text, upto 100 M documents on a single CPU);"
