The relationship maintenance phase of a reorganization restores the referential integrity defined by the rules of the latest schema definition and includes the following actions.
Adding an inverse
Removing some, but not all, inverses from a relationship (that is, after the change, inverses still exist between the properties involved)
Condition maintenance
Inverse definition changes; for example, changing the inverse-required option
Changes to dictionary specifications; for example, key definitions or the no-duplicates constraint
Changes to the physical attributes of a collection; for example, block size and expected population
Validation of the member objects of a collection against its member type definition
Validation of reference property type changes
Moving exclusive collections up or down the class hierarchy
As these structural changes are not performed online, the database is not available to applications until the reorganization completes (or fails and is aborted).