[hibernate-issues] [Hibernate-JIRA] Created: (HHH-3970) One-to-one association must return null instead of proxy (or actual object).

[Sandeep Vaid (JIRA)]

One-to-one association must return null instead of proxy (or actual object).
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                 Key: HHH-3970
                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-3970
             Project: Hibernate Core
          Issue Type: Improvement
    Affects Versions: 3.3.1
            Reporter: Sandeep Vaid
            Priority: Critical


In hibernate, presently one-to-one associations are fetched non-lazily...
 I know that this is done because, hibernate requires to fire 1 sql to find whether proxy can be created or not... 
 and if it has to fire 1 sql, then why not to load one-to-one object itself in 1 sql instead of creating proxy of it (in 1 sql).
  
 Consider my scenario..
   Product has one-to-one with ProductBasic which has one-to-one with ProductTerm
   
  Now i just queried for List of Products and i got say 300 product records.. (in 1 sql query)
  In this case i don;t require ProductBasic and ProductTerm.... but as these are one-to-one associations, there are 
  compulsorily  non-lazily fetched. Thus another 300 + 300 select queries are fired to get ProductBasic and ProductTerm
  which is surely unacceptable as there are 600 extra sql's getting fired.. The situation may become worst if i 
  have many one-to-one associations in my domain tree.
  
  I think hibernate code must be changed so that one-to-one associations should be not compulsorily  non-lazily fetched....
  
One way i could think of it is, if user has not asked to fetch one-to-one association then instead of
loading one-to-one object (or creating proxy) simply null should be returned without firing any SQL...
Later when user asks for this  one-to-one association, now fire 1 sql to get this association..

The major advantage of this approach is that if user has not asked for one-to-one association, no extra sql (unnecessary)
queries will be fired... (specially when retriving parent collection - e.q our scenario described above)..


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