A call to: OracleDataStore.getSchema() ends up calling: AttributeType JDBCDataStore1.buildAttributeType(ResultSet rs) that doesn't take into account all the information available inside the provided ResultSet for an Oracle table. For example the NILLABLE or IS_NILLABLE column is not used and so all the AttributeType will have isNillable()==false value. Other information are ignored too, like field length. Also the DefaultAttributeType implementation strangely sets isNillable=true, and minOccurs=1... This is the same bug as for PostgisDataStore: http://jira.codehaus.org/browse/GEOT-486