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Re: Property Path Profiles

From: Matt Perry <matthew.perry@oracle.com>
Date: Mon, 11 Jan 2010 13:51:11 -0500
Message-ID: <4B4B731F.1000508@oracle.com>
To: Lee Feigenbaum <lee@thefigtrees.net>
CC: W3C SPARQL Working Group <public-rdf-dawg@w3.org>
Hi Lee,

Thanks for the comments. Please find my answers to your questions below.

-Matt

Lee Feigenbaum wrote:
>
> Matt Perry wrote:
>> Hi,
>>
>> During the last TC, I mentioned the possibility of a Property Paths 
>> profile that identifies a subset of property path queries that can be 
>> expressed with SQL. Such a profile would make it easy for triple 
>> stores implemented on top of relational databases to identify the set 
>> of property path queries that they "natively" support.  The purpose 
>> of this email is to start a discussion about the possibility of 
>> property path profiles.
>>
>> The grammars below show two possible fragments that we have 
>> identified. The first grammar is for SQL + CONNECT BY (Oracle) and 
>> the second is for PLAIN SQL.
>>
>> CONNECT BY:
>>
>> ALT  -> URI | URI|ALT
>> SEQ  -> URI | URI/SEQ
>> Elem -> URI | SEQ   | ALT   | ^URI
>> COMP -> URI | Elem* | Elem+ | Elem{n,m} | Elem?
>> TOP  -> URI | COMP  | ALT   | SEQ       | ^URI
>>
>> PLAIN SQL:
>>
>> ALT  -> URI | URI|ALT
>> SEQ  -> URI | URI/SEQ
>> Elem -> URI | SEQ       | ALT   | ^URI
>> COMP -> URI | Elem{n,m} | Elem?
>> TOP  -> URI | COMP      | ALT   | SEQ   | ^URI
>
> Are the Plain SQL set simply the set that can be expanded as a 
> (possibly complicated) SPARQL 1.0 query string? (This is sort of but 
> not exactly what's termed a "simple path" in the current doc.)
Yes. I guess this would be somewhat redundant.
>
> Do other DBMSes included equivalent/similar functionality to CONNECT 
> BY? I'm hesitant to go down a multi-level conformance path in the 
> first place, but I'd be even more hesitant to do so if it were just in 
> the context of a single DBMS.
Yes. Both SQL Server and DB2 support recursive common table expressions, 
which provide the same basic functionality.
>
> Lee
>
>>
>> Thanks,
>> Matt
>>
>>
>>
>>
Received on Monday, 11 January 2010 18:52:03 GMT

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