- Solr and Sphinx can meet all your requirements. They are fast and aim to efficiently index and search large amounts of data.
- Both have a list of high-traffic sites that use them (Solr, Sphinx)
- Both provide commercial support. (Solr, Sphinx)
- Both provide client API bindings for multiple platforms / languages (Sphinx, Solr)
- Both can be distributed to increase speed and capacity (Sphinx, Solr)