We are currently considering implementing Hibernate and are excited about it's lazy-load capabilities because it will allow our domain objects to be fully functional without having to worry about whether their relationships have been loaded. However, there are certain scenarios where we might want to do an outer join to force an object and its relationships to be loaded with a single SQL statement (for performance, when we know they will be needed and perhaps lazy loading is not performing at the level we need).

Is it possible to programatically alter the lazy loading characteristics of an object relationship at runtime, according to how our application may need to use an object in different situations, or are the o/r mappings fixed at deploy time?

Thanks,

In HQL, use the fetch keyword

Is there a Criteria API equivalent to the HQL FETCH keyword?

Yes: http://www.hibernate.org/hib_docs/reference/html/query-criteria.html#query-criteria-s5

Thanks Michael.

I must have had a brain-fade while I was reading the doco, I completely missed that.

I notice that the example sets eager fetch mode for two collections at once. Will that work? I ask becase isn't the HQL access method limited to one FETCH keyword per HQL statement?

So, in this instance, the Criteria API access method is more powerful than the HQL access method?

Yes, this should work. So in this case the Criteria API is more powerful.

Note that HQL isn't limited to one FETCH per query - it's limited to one "collection" FETCH per query. You can FETCH multiple single object relationships in HQL.

Also, even though you can specify multiple fetch modes using the Criteria API, that doesn't necessarily mean it can execute in a single query. AFAIK, a similar limitation applies: only one collection may be fetched in a single query. The difference is the Criteria API will execute multiple queries to satisfy the request if necessary (atleast this is the behavior I've observed).

Joe