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Summary of open issues on query.

From: Andy Seaborne <andy.seaborne@talis.com>
Date: Wed, 03 Feb 2010 08:42:23 +0000
Message-ID: <4B6936EF.7060106@talis.com>
To: SPARQL Working Group <public-rdf-dawg@w3.org>
Here is my recollection of the status of query related open issues.

   ?? for still unresolved.

   DONE, for where I think we have agreement or proposal to go in the doc.

	Andy

ISSUE-3
Subquery syntax (e.g. mandatory curly braces
   DONE - use {}

ISSUE-4
What is the variable scope between main queries and subqueries
   DONE - join scoping subject to projection.

ISSUE-5
ASK queries in FILTERs
   ?? (related -- EXISTS in FILTERS)

ISSUE-6
SELECT queries in FILTERs
   ??

ISSUE-7
CONSTRUCT & DESCRIBE queries in FROM [NAMED]? 	
   ??
   CONSTRUCT not needed if bNodes can be introduced by constructor.

ISSUE-8
What determines the RDF dataset for subqueries?
   DONE - Same as outer query - no FROM in subqueries.

ISSUE-12
Presence and syntactic detail of HAVING clause 	
   DONE (it's like a FILTER with the word HAVING)

ISSUE-13
Subqueries in HAVING analogous to subqueries in FILTERs 	
   ??
   ** Related to ISSUE-6

ISSUE-14
Which aggregates to include 	
   ?? but proposal in current doc.

ISSUE-15
Extensibility of aggregate functions 	
   DONE
   We're having URIs and function call syntax is function call IIRC.
   Not the special AGG form.

ISSUE-16
Dealing with aggregates over mixed datatypes 	
   ??
   Related to ISSUE-53

ISSUE-29
Should negation be done via a binary operator on subqueries, a binary 
operator within graph patterns, or a filter+subquery? 	
   ??
   This is MINUS / NOT EXISTS issue.

ISSUE-35
Can aggregate functions take DISTINCT as an argument a la SELECT 
COUNT(DISTINCT ?X)? 	

   DONE  All built-in aggregates can take the word DISTINCT.
   Custom ones do not; it's part of their definition,
   i.e. different URIs for a DISTINCT and non DISTINCT form.

ISSUE-36
What happens when expressions are projected with the same name as an 
existing variable? 	
   DONE  Current doc proposes this is a static error.

ISSUE-39
Can variable used as aliases for expressions be themselves used in other 
expressions? 	
   DONE
    Scope starts at point of definition - can use to the right and outer 
scope.

ISSUE-41
Does GROUP BY allow variables or expressions, and does it allow mutiple 
expressions? 	
   ??
   (I hope it does - it's just key calculation)

ISSUE-53
How are unbounds and errors treated in aggregate evaluation? 	
   ??
   Related to ISSUE-16
Received on Wednesday, 3 February 2010 08:42:30 GMT

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