Question

Which is the best method(performance wise) to delete an object if only its id is available.

1. HQL. Will executing this HQL load the SessionContext object into hibernate persistence context ?

   for(int i=0; i<listOfIds.size(); i++){
       Query q = createQuery("delete from session_context where id = :id ");
           q.setLong("id", id);
           q.executeUpdate();
   }
   

2. Load by ID and delete.

   for(int i=0; i<listOfIds.size(); i++){
       SessionContext session_context = (SessionContext)getHibernateTemplate().load(SessionContext.class, listOfIds.get(i));
       getHibernateTemplate().delete(session_context) ;
   }
   

Here SessionContext is the object mapped to session_context table.
Or, well off course is there an all together different and better approach ?

Answer 1

Out of the two, the first one is better, where you will save memory. When you want to delete the Entity and you have the id with you, writing a HQL is preferred.

In you case there is a third and better option,

Try the below,

//constructs the list of ids using String buffer, by iterating the List.
String idList = "1,2,3,....."

Query q = createQuery("delete from session_context where id in (:idList) ");
q.setString("idList", idList);
q.executeUpdate();

Now if there are 4 items in the list only one query will be fired, Previously there would be 4.

Note:- For the above to work, session_context should be an independent table.