Thompsonbry.systap added a comment. There are two known issues with the property path operator that Nik and I discussed today. These are [1] and [2]. The first of these issues means that the operator is actually fully materializing the property paths *before* giving you any results. [1] is a ticket to change that an do incremental eviction of the results. That will fix the "liveness" issue you are seeing with that path expression. The other ticket deals with another problem where the property path operator can become CPU bound if the necessary access paths are in cache since there is no IO Wait. However, I suspect that [2] will disappear when we address [1]. As for the timing on this, we can elevate this to a critical issue and get it done in our next sprint for the 1.5.1 release.
Nik and I also discussed the inference vs materialization question as it relates to property paths. Out of all the property hierarchies, only the geo-political one involves transitive traversal up more than a single predicate. I suspect that (with the fix to [1]) that you can easily use property paths for all such expressions. The draft of SPARQL property path support included a mechanism to bind the actual path onto variables. Unfortunately this did not make it into the final specification of property paths. Using property paths you can specify the path as a regular expression of predicates to be traversed, but you can not extract the actual vertices along that path. However, the blazegraph property path operator internally *does* support this along with minimum and maximum traversal limits. The ALP (Arbitrary Length Path) Service [3] exposes all of this using an ASTOptimizer. See ASTALPServiceOptimizer in the 1.5.0 release. It is pretty scarce on documentation. I will fix that. I will also add a page on our wiki for this. Thanks, Bryan [1] http://trac.bigdata.com/ticket/1003 (Property path operator should output solutions incrementally) [2] http://trac.bigdata.com/ticket/994 (Property Path operator can become CPU bound) [3] http://trac.bigdata.com/ticket/1072 (Configurable ALP Service) TASK DETAIL https://phabricator.wikimedia.org/T90116 REPLY HANDLER ACTIONS Reply to comment or attach files, or !close, !claim, !unsubscribe or !assign <username>. EMAIL PREFERENCES https://phabricator.wikimedia.org/settings/panel/emailpreferences/ To: Smalyshev, Thompsonbry.systap Cc: Thompsonbry.systap, Beebs.systap, Haasepeter, Aklapper, Manybubbles, jkroll, Smalyshev, Wikidata-bugs, Jdouglas, aude, GWicke, daniel, JanZerebecki _______________________________________________ Wikidata-bugs mailing list Wikidata-bugs@lists.wikimedia.org https://lists.wikimedia.org/mailman/listinfo/wikidata-bugs
