On 18 May 01, at 15:41, Linda DeMichiel wrote:
> Is the semantics of ordering defined by the database semantics (e.g.
> SQL semantics) or by Java semantics? While maintaining Java semantics
> would seem desirable, it means that we cannot generally push the
> ordering down into the database, because these semantics may differ,
> most notably in the case of strings, where the semantics of comparison
> are further dependent on the particular representation chosen for
> strings in the persistent store.
Hi Linda
Thanks for explaining the issues related to the "order by"
functionality in EJB QL. In my opinion: "the best is the enemy of
the good." Provide for a java.util.List return from queries and an
"order by" clause in EJB QL. Defer the exact semantics of the
comparison to the EJB container as implementation dependent.
(The EJB container can then defer the semantics to the persistent
store if it chooses.)
In my opinion (as a vendor of an EJB 2.0 persistence manager:
www.mvcsoft.com), most users will find this satisfies their
business requirements. The remainder can implement a sort
themselves.
> With regard to List representations for cmr-fields, we will also have
To me, this isn't nearly as important an issue, as the same entities
can be retrieved as an ordered list with a query (assuming that
"order by" is added to EJB QL).
Thanks again for sharing these issues with the list.
-Dan O'Connor
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