The project (where Sphinx applied later) started 2009 had large database of emails , contacts and various business transaction records. It was done with PHP and MySQL. The project had had to be long-standing, and the database was growing fast. After couple years we’ve felt lack of fine full-text search. For that time the MySQL build-in fulltext indexes haven’t been available yet as it was implemented in v5.5. After the quick review of some open source tools for full text search we decided to use the Sphinx.