[Mulgara-dev] Problem w/ "insert select ..."

Andrae Muys andrae at netymon.com
Thu Mar 29 03:36:22 UTC 2007


On 29/03/2007, at 11:08 AM, Eric Brown wrote:

>
> I also tried inserting into a different model -- same error. It  
> also seemed like I should have been able to make the query simpler  
> -- insert select $s <http://rdf.topazproject.org/RDF/ 
> organizationType> 'bar' from <...> where $s <http:// 
> rdf.topazproject.org/RDF/organizationType> 'foo' into <...> --  but  
> that's how I saw the error the first time and expanded it just in  
> case mulgara was demanding variables instead of just tuples.
>
> I can open a JIRA issue, but I thought I'd double check that it  
> isn't something stupid I'm doing first.

This is a known bug, http://mulgara.org/jira/browse/MGR-43.  The  
simpler query you mention is indeed the intended phrasing.

> BTW, What I'm really need to do is insert followed by delete. It  
> would be nice if ITQL had a "update select ..." or "replace  
> select ..." ability.

Neither update nor replace have any meaning when working with rdf.   
Updating a _property_ of an _instance_ is an operation that only  
makes sense when you have a concept of an _instance_ ---  
correspondingly update is an rdfs level operation.  What mulgara does  
provide is the concept of a transaction.  OTOH I would like to see  
improved support for compound operations.  Something along the lines  
of haskell's do syntax combined with a query/operation monad.  I've  
been referring to this as let-expressions, but really it about  
providing the ability to integrate side-effects (insert/delete)  
cleanly into sequences/sets of queries.

Andrae

-- 
Andrae Muys
andrae at netymon.com
Principal Mulgara Consultant
Netymon Pty Ltd





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