3.5.2. Outer Join Fetching
If your database supports ANSI or Oracle style outer joins, outer join fetching might increase performance by limiting the number of round trips to and from the database (at the cost of possibly more work performed by the database itself). Outer join fetching allows a graph of objects connected by many-to-one, one-to-many or one-to-one associations to be retrieved in a single SQL SELECT.

By default, the fetched graph ends at leaf objects, collections, objects with proxies, or where circularities occur. For a particular association, fetching may be enabled or disabled (and the default behaviour overridden) by setting the outer-join attribute in the XML mapping. Outer join fetching may be disabled globally by setting the property hibernate.use_outer_join to false. You may limit the maximum depth of the fetched graph of objects using hibernate.max_fetch_depth.


This is what i read in the Hibernate Document,Chapter 3.

There is two question:
1. What's "Outer Join Fetching",Does it mean that "Select * from User U,Trade T where U.user_id = T.user_id" is an outer join fetching?

2. What's "ANSI"?

This first link should help you.

The second is even better

And finally