- From: Polleres, Axel <axel.polleres@siemens.com>
- Date: Sun, 1 Apr 2012 22:32:25 +0200
- To: "public-rdf-dawg@w3.org" <public-rdf-dawg@w3.org>
Dear all, thanks Andy and Greg for further clarifying the discussion. Let me try, along the lines of http://lists.w3.org/Archives/Public/public-rdf-dawg/2012JanMar/0262.html to summarize the options on the table (I left out option 4, since it was canceled out before being voted upon in the Telco 2 weeks ago and added options 6 and 7 as discussed in the mail, as well as option 8 (which was "in the air" in the last telco if I understood it correctly). As to Lee's earlier summary, I added the votes two weeks ago, as well as an item estimating the danger of "lock-in". (will send a proposed way forward in a separate mail, since I have to send regrets for the upcoming telco) 1) Leave as is, no change + Does not require a new last call + Does not open up any potential _new_ issues from aspects of new design(s) - Almost surely results in a formal objection from the various commenters about the counting property path execution complexity issue - Potentially hamstrings some use cases of property paths, depending on whether all non-counting pp instances can be rewritten as SELECT DISTINCT subqueries - lock-in to counting semantics as default - Strwapoll on http://www.w3.org/2009/sparql/meeting/2012-03-20 : 2 x +1 6 x 0 1 x -1 (Paul) 2) Add DISTINCT(path) and {+}/{*} operators + Addresses the commenters' concerns JP-4(as per informal discussions with some of them offlist) + Gives query authors significant expressivity in choosing the path counting semantics vs. performance tradeoff they want - Requires a new last call - Raises the burden to implement property paths - New design may have unknown interactions between counting and non-counting operators in the same path - Strwapoll on http://www.w3.org/2009/sparql/meeting/2012-03-20 : 2 x +1 6 x 0 1 x -1 (Steve) 3) Add DISTINCT(path) only + Addresses the commenters' concerns (as per informal discussions with some of them offlist) + Gives query authors some expressivity in choosing the path counting semantics vs. performance tradeoff they want - Requires a new last call - Raises the burden to implement property paths (but not as much as #2) - lock-in to counting semantics as default (new: raised by greg) - Strawpoll on http://www.w3.org/2009/sparql/meeting/2012-03-20 : 8 x +1 2 x 0 5) Mark property paths as non-normative +/- Not sure if this requires a new last call + Lowers implementation burden + no lock-in to counting- or non-counting semantics for future specs - Removes a significant feature from SPARQL 1.1 Query - May lead to formal objections within the working group - Strawpoll on http://www.w3.org/2009/sparql/meeting/2012-03-20 : 6 x 0 3 x -1 (Andy, Matt, Paul) 6) change the semantics of * and + only, leave everything else as in LC, cf. http://lists.w3.org/Archives/Public/public-rdf-dawg/2012JanMar/0285.html http://lists.w3.org/Archives/Public/public-rdf-dawg/2012JanMar/0286.html - Requires a new last call - May lead to formal objections within the working group? +/- unsure whether it addresses commenters (mixing counting and non-counting) + more intuitive for common reachability use cases than option 3 7) Add ALL(path) only, and change default to DISTINCT(path) - Requires a new last call - May lead to formal objections within the working group? - lock-in to non-counting semantics as default + addresses commenters (for sure JP-4, who suggested this, not sure about JB-10, WM-1) + more intuitive for common reachability use cases than option 3 8) Add ALL(path) and DISTINCT(path), and one alternative being obligatory - Requires a new last call +/- May lead to formal objections within the working group? (not sure) + no lock-in to counting or non-counting semantics as default + probably addresses commenters (for sure JP-4, who suggested this, not sure about JB-10, WM-1) ---------------------- -- Dr. Axel Polleres Siemens AG Österreich Corporate Technology Central Eastern Europe Research & Technologies CT T CEE Tel.: +43 (0) 51707-36983 Mobile: +43 (0) 664 88550859 Fax: +43 (0) 51707-56682 mailto:axel.polleres@siemens.com
Received on Sunday, 1 April 2012 20:32:53 UTC