I was testing lazy-loading of 1:1 extension tables, by adding the lazy attribute to the <one-to-one /> element. As expected, when I load the entity and attempt to access the lazy property outside a session, I receive a LazyLoadException. However when examining the SQL generated, NH still includes the OUTER JOIN to the secondary table. Looks like a bug to me, but I wanted to solicit some feedback.
The addition of the lazy attribute to the xsd and comments within the NH code suggest lazy loading should be supported for 1:1 extensions.
