[Hibernate] HQL 3.1

[Gavin King]

One of the main reasons we migrated to the new query parser was to allow 
for easier extension of HQL. We didn't actually make much in the way of 
HQL extensions in 3.0 (except for UPDATE/DELETE, CASE and EJB-QL 
functions). I've been wondering what new cool stuff we could consider 
for 3.1.

First, we need to add a way to add extra conditions to outer joins. Eg:
  from Order ord
     left join ord.lines line on line.deleted is false
  where ...
But perhaps "on" is the wrong keyword, since it is an "extra" join 
condition. Perhaps "filter by"?

  from Order ord
     left join ord.lines line filter by line.deleted is false
  where ...
I'm not sure.
Next, it's about time we had a reliable instanceof operator:
  from Payment p
  where p instanceof Cheque
     or ....
Next, I'm considering adding more query-level control over fetching 
strategies

  from Order ord
     subselect fetch ord.lines
  from Order ord
     select fetch ord.lines
  from Order ord
     batch fetch ord.lines
  from Order ord
     batch size 10 fetch ord.lines
Finally, we need to grapple with the problem of supporting expressions 
in the select clause.

Do you think we could and should support the ANSI SQL style periods and 
temporal operators (overlaps, during, before, after, etc.) in a portable 
way?

  from Contract c where [c.effectiveStartDate, c.effectiveEndDate] 
overlaps (:start, :end]

(Unfortunately, Java has no Period or Interval class that we could 
create a standard Hibernate Type for.)

Any other ideas?
--
Gavin King
+61 410 534 454
+1 404 822 8349
callto://gavinking
Hibernate
[EMAIL PROTECTED]
http://hibernate.org
JBoss Inc
[EMAIL PROTECTED]
http://jboss.com

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