If an entity is retrieved previously within a session - in most cases - it does not have to be retrieved again since it is stored in the session cache.
So, multiple BO reads against Java-backed MO's do not re-execute SQL.
The exception is when a call to COBOL is made. Since Java does not know what COBOL could have changed, the entities must be refreshed from the database. Similary BO Reads against COBOL will always re-execute SQL.
Copyright © 2013, Oracle and/or its affiliates. All rights reserved.