Managing a big set of data using JCR in production environment sometimes requires special operations with Indexes, stored on File System. One of those maintenance operations is a recreation of it. Also called "re-indexing". There are various usecases when it's important to do. They include hardware faults, hard restarts, data-corruption, migrations and JCR updates that brings new features related to index. Usually index re-creation requested on server's startup or in runtime.