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Clarification of the meaning of "unaggregated variable"

From: Matthew Horridge <matthew.horridge@stanford.edu>
Date: Thu, 2 Jul 2015 09:12:03 -0700
Message-Id: <A53FC37C-0795-45BF-AB3A-3BE15004DB3E@stanford.edu>
To: public-sparql-dev@w3.org

I’ve been reading through the definition of SPARQL in the SPARQL 1.1. Query Language Document.  In particular, section 18.2.4, which describes how to convert aggregate queries into the SPARQL algebra.  

The algorithm listed in, which I’ve pasted in below talks about “unaggregated variables”.  However, there isn’t a definition for “unaggregated variable” in the spec, and it isn’t totally clear to me what an “unaggregated variable” is.  If anyone could provide me with a precise definition for what an “unaggregated variable” is, and thus clarify this part of the spec, I would really appreciate it.

Thanks a lot,


For each (X AS Var) in SELECT, each HAVING(X), and each ORDER BY X in Q
  For each unaggregated variable V in X
      Replace V with Sample(V)
  For each aggregate R(args ; scalarvals) now in X
      # note scalarvals may be omitted, then it's equivalent to the empty set
      Ai := Aggregation(args, R, scalarvals, G)
      Replace R(...) with aggi in Q
      i := i + 1
Received on Friday, 3 July 2015 00:17:24 UTC

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