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openlink / virtuoso-opensource

Virtuoso is a high-performance and scalable Multi-Model RDBMS, Data Integration Middleware, Linked Data Deployment, and HTTP Application Server Platform
https://vos.openlinksw.com
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Some graphs aren't listed on VOS7 #80

Open okbp opened 11 years ago

okbp commented 11 years ago

In develop/7 and stable/7, some graphs aren't listed via the below sparql.

SELECT DISTINCT ?g WHERE { GRAPH ?g { ?s ?p ?o }}

For example, there are 22 graphs but it returns only 16 graphs. And Conductor (Linked Data - Graphs) displays same list.

But this query returns all graph names.

SELECT ?g WHERE { GRAPH ?g { ?s ?p ?o }} GROUP BY ?g

What is the difference between two queries?

JulienCojan commented 11 years ago

Hi,

I noted as well a performance drop for queries over graphs. I often have a timeout on this query :

select distinct ?g where { graph ?g {?s ?p ?v} } limit 1

when this had a result straight away with Virtuoso 6.1.6, same data. Adding group by improves the computation time, but it is still slower that before.

hodade commented 8 years ago

GROUP BYの方は空のグラフも出てくるみたいですね。