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Re: Question about BINDINGS

From: Andy Seaborne <andy.seaborne@epimorphics.com>
Date: Wed, 06 Oct 2010 15:07:15 +0100
Message-ID: <4CAC8293.8000009@epimorphics.com>
To: Axel Polleres <axel.polleres@deri.org>
CC: SPARQL Working Group <public-rdf-dawg@w3.org>


On 06/10/10 14:36, Axel Polleres wrote:
>> 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.
>
> Just to understand this:
> What you say here is that the syntactic sugar of "BINDINGS" makes it easier to process that bit for engines that understand it than the uglier, but equivalent version with UNION subqueries, yes?
> (which would coincide with my undertanding)

You can't execute the query until you see it but if you see the 
query+which variables are in the bindings, you can deduce whether 
certain execution strategies are possible and even start executing for 
data seen so far. If you see the data first, you can't decide on the 
execution until you see the query part.

By the way, as we move towards LC it's probably more efficient to tie 
comments and questions back to the text.

	Andy
Received on Wednesday, 6 October 2010 14:07:55 GMT

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