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Re: Graphs Design 6.2

From: Richard Cyganiak <richard@cyganiak.de>
Date: Wed, 25 Apr 2012 21:45:20 +0100
Cc: public-rdf-wg WG <public-rdf-wg@w3.org>
Message-Id: <A531F179-01F1-453D-89A7-4EAB16FD72B4@cyganiak.de>
To: Steve Harris <steve.harris@garlik.com>, Sandro Hawke <sandro@w3.org>
Hi Steve,

On 25 Apr 2012, at 19:54, Steve Harris wrote:
>> @union is just syntactic sugar in TriG, shorthand for having to
>> repeat all the triples in all the named graphs.
>> 
>> Does that change your mind about it, at all?
> 
> Not really.
> 
> The implication of that would be that if I see @union I have to disable an optimisation that's designed specifically to handle that (common) case.

Why do you need to disable the optimisation? If your store has the optimisation (union default graph), then you already know that it will automatically do what @union asks for, so you just have to load the named graphs and are done.

If your store *didn't* have a union default graph, only then it would have to do something special when it sees @union: load every triple twice, both into a named graph and into the default graph.

> I don't see how it makes ay sense to allow a data format to specify that behaviour, it should normally be up to the query author.

@union doesn't specify behaviour. It specifies what triples are in the default graph of the serialized dataset. It doesn't dictate what happens when you load that dataset into a store.

Best,
Richard
Received on Wednesday, 25 April 2012 20:45:50 UTC

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