Fedora maintains a set of internal indices containing information derived from the persistent storage, namely the underlying OCFL (Oxford Common File Layout). These indices act only as a cache of information that is persisted in the underlying OCFL and can be destroyed and rebuilt as necessary.
These indices currently maintain the following information:
- the LDP containment hierarchy
- resource membership relationships
- relationships between resources
- searchable fields, and
- the relationship between Fedora resources and their associated OCFL objects.
These indices are built initially when Fedora is started for the first time on a non-empty OCFL. As content is added, updated and deleted, the indices are updated accordingly. You may at some point wish to rebuild these indices from scratch for a variety of reasons. For example, it is likely that a future change (in subsequent releases) to the index structures could require a rebuild. In that case you can accomplish this task by simply restarting Fedora with the following flag:
-Dfcrepo.rebuild.on.start=true
NOTE: Depending on the size of your repository, the type of database, and/or the capacity of your database server, the rebuild can take anywhere from a few seconds to several hours (i.e if you have many millions of objects).
