I have more than 2GB of offline messages and got:
org.jivesoftware.openfire.OfflineMessageStore - Internal server error
java.sql.SQLException: Numeric Overflow
at oracle.jdbc.driver.NumberCommonAccessor.throwOverflow(NumberCommonAccessor.java :4381)
at oracle.jdbc.driver.NumberCommonAccessor.getInt(NumberCommonAccessor.java:132)
at oracle.jdbc.driver.OracleResultSetImpl.getInt(OracleResultSetImpl.java:942)
at org.jivesoftware.openfire.OfflineMessageStore.getSize(OfflineMessageStore.java: 428)
at org.jivesoftware.openfire.admin.offline_002dmessages_jsp._jspService(offline_00 2dmessages_jsp.java:227)