It's even worse... If you use composed fields... and if you need eventually to perform a JOIN... you will need to do something like WHERE SUBSTRING(COMPOSED_FIELD,1,5) = "DESTINATION" or something like that... Besides... if you need to support a different system, you change PersitenceManager, or implement a new one. Also... Tim wrote : Well... with your logic, eventually you would end up with 100 column tables, some columns null, some not depending on which particular message type is used. If you have 100 systems... it's better to have 100 columns than a single column with 100 substrings to deal with. :-) also.. you could have something pluggable that would enable/disable fields creation according to used features. (if that happens some day) View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4011727#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...