Techniques of index clustering for full text search engines are described herein. In one embodiment, a full text search is performed by a search node using a local copy of an index within the searching node during a search session. In response to an update of a list of data entries the relational database through a Common API (common in the sense the update triggered to the relational DB will also trigger an index change), an index update event is scheduled to update a master copy of the index directory. Periodically the local copy of the index directory is updated by copying index data from the master copy of the index directory (totally or incrementally). Other methods and apparatuses are also described.