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https://issues.apache.org/jira/browse/JDO-751?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15338646#comment-15338646
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Tilmann Zäschke commented on JDO-751:
-------------------------------------

Thanks for the feedback.
1. Yes, you are right, and I do not expect the passed in persistent object to 
be equal to any database object. It is only compared to itself (which should 
return 'equal') and to 'null' (which should return 'not equal')
2. Okay, but I would expect the query engine of an DBMS to take care of that 
and apply the same 'truncation' to query parameters as it applies to stored 
values. So in the worst case it should return additional results that have a 
very similar timestamp, or not? The two dates that I use are over 15 minutes 
apart, so I wouldn't expect a problem here. I can adjust this if this turns out 
to be a problem.
3. Hmm, I think if {{ref.ref.id}} is common and use of Optional becomes common, 
then {{optional.optional.id}} may also become common ... . As simple example 
would be a family database where I want to find all grandchildren of a person 
via {{father.father.id == 33}} (and 3 similar queries).

A separate question (discussed in the meeting) is whether we really want to 
have {{orElse}} in WHERE clauses, or whether we should limit it to SELECT 
clause. For SELECT clauses we at least have a good use case (provided by Andy), 
for WHERE we don't really have that yet.

> Support for Java8 Optional
> --------------------------
>
>                 Key: JDO-751
>                 URL: https://issues.apache.org/jira/browse/JDO-751
>             Project: JDO
>          Issue Type: New Feature
>          Components: specification, tck
>            Reporter: Andy Jefferson
>             Fix For: JDO 3.2
>
>         Attachments: JDO-751-tck-patch-v4.txt
>
>
> java.util.Optional provides a feature that is available in other languages. 
> Since JDO 3.2 will be for Java8+ then it makes sense to add support for this 
> as a "supported persistable type"



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