Jason Your query as written results in large cross products as far as I can see.
The middle section of your query which is outside of the unions makes no reference to the previously bound sensor variable so the query is forced to cross product all the sensors with all the rooms. A simple fix may be to move that section of the query to after the final union. A better fix might be to move that portion of the query into both branches of the final union. Please don’t remove prefixes from queries. It prevents people from simply copying and pasting those queries into other tools directly for analysis The other thing to consider is the version being used. There are some improvements to property path handling in the just released 3.1.1 which may also improve things. Rob On 09/11/2016 06:07, "Jason Koh" <[email protected]> wrote: Dear all, I am Jason Koh from Brick community (http://brickschema.org/). I try to run a SPARQL query on a graph, and it takes forever on Fuseki. Environment: Windows 10, i5, 8 GB RAM Graph size: 4000 triples The query: ############ (prefixes are omitted here.) SELECT DISTINCT ?sensor ?room WHERE { { ?sensor rdf:type/rdfs:subClassOf* brick:Zone_Temperature_Sensor . } UNION { ?sensor rdf:type/rdfs:subClassOf* brick:Discharge_Air_Temperature_Sensor . } UNION { ?sensor rdf:type/rdfs:subClassOf* brick:Occupancy_Sensor . } UNION { ?sensor rdf:type/rdfs:subClassOf* brick:CO2_Sensor . } ?vav rdf:type brick:VAV . ?zone rdf:type brick:HVAC_Zone . ?room rdf:type brick:Room . ?vav bf:feeds+ ?zone . ?zone bf:hasPart ?room . {?sensor bf:isPointOf ?vav } UNION {?sensor bf:isPointOf ?room } } ####### Background knowledge: I would like to find all the sensors that are subclass* of the above sensor types in all rooms. A sensor may be a sensor of a room or VAV, which is equipment serving a room. Is this a just not reasonable query and should I divide it into several queries such as one for rooms and one for sensors belonging to the rooms? Short intro to Brick: It is a building ontology to describe resources in buildings comprehensively. Github repo with ontology : https://github.com/BuildSysUniformMetadata/GroundTruth A webpage under construction : http://brickschema.org/ Paper: https://people.eecs.berkeley.edu/~gtfierro/papers/brick.pdf Thank you. With regards, Jason Koh cseweb.ucsd.edu/~jbkoh
