The source code is the only worthwhile documentation I've found so far. I am trying to find examples on usage of the _sql predefined field but cannot locate it in any sources.

Thanks Nicolas, I'm not a big fan of ORM and the OpenERP one is at times confounding to me due to it's entity identity handling. I prefer a little more control but keep resisting the urge to bypass ORM and cursor execute my own queries. Have a nice day too!

I think I have chosen the safer solution now. It is also much faster than refactoring my code only to run into the same errors again and again. I have models V m2m C, C m2m D, C o2m N, D m2o E and they work fine except from the level of V where it all blows up. Uncaught exceptions within ORM module only, not my models. At most this is a query with 3 joins so now I am putting that query into a view and building model from the view. My class diagrams are valid but ORM just cannot handle it. It creates intersect tables with no constraints - bad referential integrity that....

@mike what do you mean by "putting that query into a view and building model from the view.." , can you be more specific?

Instead of using a table in postgres use a view - http://www.postgresql.org/docs/8.3/static/sql-createview.html and then build your model against that view as though it were a table. The model must have _auto = False to prevent OpenERP from creating a new table.