You could access the source code in the extension library to investigate what methods are available. For example, in the most recent release, you could find the source code for jdbcRowSet here:
.\ExtensionLibraryOpenNTF-901v00_08.20140729-0805.zip\srcOpenNTF.zip\eclipse\plugins\com.ibm.xsp.extlib.relational\src\com\ibm\xsp\extlib\relational\jdbc\model\JdbcRowSetAccessor.java
Alternatively for jdbcQuery, see JdbcDataBlockAccessor.java in the same directory