Re: [cmis] queries, joins and objects

[David Caruana <david.caruana@alfresco.com>]

Hi Florent,

That's a good point. The select list is really driving the kind of  
result set, not join vs no-join. It's just that the select list is  
limited in no-join scenario. This reminds me of Hibernate where the  
query language and result set allow for both row-based and object- 
based queries (which itself is driven from select list).

I don't have an answer to how to represent the result set, but I  
agree, where possible it would be good to decorate result set row with  
object info, or treat result row as object. But we do have to cater  
for the case where a row may map to multiple objects. Do we ignore all  
but one, or attempt to provide object info for all of them. In the  
case of getChildren there's only ever one object per row.

Dave


On 1 Jul 2009, at 10:56, Florent Guillaume wrote:

> Hi,
>
> We've discussed queries and returning objects quite a few times, and  
> it's been mentioned several times that when you do a query with a  
> JOIN, then you can't get objects returned.
>
> I'd like to stress that the above is true in general, but not  
> always, far from it. Here's a common example of a JOIN that will  
> return objects:
>
>  SELECT doc.* FROM Document doc JOIN Relation rel ON ( rel.TargetId  
> = doc.ObjectId ) WHERE rel.foo = 123
>
> To me this shows that objects returned from queries, even with  
> JOINs, should be treated mostly in the same way as objects returned  
> from getChildren (which itself will be implemented as an internal  
> query for many vendors).
>
> Florent
>
> -- 
> Florent Guillaume, Head of R&D, Nuxeo
> Open Source, Java EE based, Enterprise Content Management (ECM)
> http://www.nuxeo.com   http://www.nuxeo.org   +33 1 40 33 79 87
>
>
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