how to override hibernate fetching strategy at runtime

Question

i saw following statement in book "hibernate in action". anyone can tell me how to override strategy at runtime. and can you do opposite way that is i have fetching strategy set lazy as false and i want to set it true?

“Lazy fetching lets you decide how much of the object graph is loaded in the first database hit and which associations should be loaded only when they’re first accessed. Lazy fetching is a foundational concept in object persistence and the first step to attaining acceptable performance. We recommend that, to start with, all associations be configured for lazy (or perhaps batched lazy) fetching in the mapping file. This strategy may then be overridden at runtime by queries that force eager fetching to occur.”

Answer 1

If you're using HQL for your queries, you can specify your eager fetching using the "fetch" keyword, like so:

from Cat as cat     inner join fetch cat.mate     left join fetch cat.kittens child     left join fetch child.kittens 

If you're using the Criteria Query API, you can specify the fetch mode using setFetchMode

List cats = sess.createCriteria(Cat.class)     .add( Restrictions.like("name", "Fritz%") )     .setFetchMode("mate", FetchMode.EAGER)     .setFetchMode("kittens", FetchMode.EAGER)     .list(); 

Answer 2

Use fetch profiles: http://docs.jboss.org/hibernate/core/3.5/reference/en/html/performance.html#performance-fetching-profiles