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Re: Question about BINDINGS

From: Andy Seaborne <andy.seaborne@epimorphics.com>
Date: Wed, 06 Oct 2010 09:12:23 +0100
Message-ID: <4CAC2F67.7020305@epimorphics.com>
To: Axel Polleres <axel.polleres@deri.org>
CC: SPARQL Working Group <public-rdf-dawg@w3.org>


On 05/10/10 20:13, Axel Polleres wrote:
> looking over the minutes from last time and trying to understand the conclusion of  the BINDINGS discussion...
>
> Do I miss anything or is semantically just the same as a Subquery:
>
> i.e.
>
> WHERE  { P ]
> BINDINGS ?X1 ... ?Xn { ( c11 ... c1n ) (c21 ... c2n) ... }
>
>
> just boils down to
>
>
> WHERE { { P }
>   { {SELECT ( c11 AS ?X2 )  ... ( c1n AS ?Xn ) WHERE {} }
>     UNION
>     {SELECT ( c21 AS ?X2 )  ... ( c2n AS ?Xn  ) WHERE {} }
>     UNION
>     ...
>   } }

Sort of.  That syntax translation needs to put the constants inside 
WHERE clause and needs tweaking to cope with UNDEF.  The subquery 
SELECT-UNION-WHERE-{} can be used to insert constants but breaks the 
streaming possibilities given by BINDINGS which present query, then 
variables then the data.

	Andy
Received on Wednesday, 6 October 2010 08:13:00 GMT

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