Sun Java System Directory Server Enterprise Edition 6.2 Reference

Case Sensitivity in JDBC Data Views

In some cases, the LDAP attribute might be case insensitive, while the corresponding column in the relational database is case sensitive. Directory Proxy Server handles this by adding an UPPER keyword to equality and substring indexes. This can have serious performance implications. If the relational database requires case-sensitivity, you should therefore create specific indexes on the upper case values.