The XDB Server supports schema level domain and referential integrity constraints. While integrity checking is a valuable facility, it can impact database performance considerably, especially on UPDATE, INSERT and DELETE operations.
You must determine whether the advantages of schema level integrity constraints outweigh the additional time required to enforce them. You might want to eliminate some of these checks at the schema level, and instead perform them through the validation facilities of the front-end data entry application. Remember that in a LAN environment use of integrity features creates additional network traffic.
Note that some indexes are automatically created and maintained by the system when integrity constraints are imposed on the database. These indexes can be dropped only by dropping the associated constraints.
For more information about referential constraints, see the following in the SQL Reference: