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https://issues.apache.org/jira/browse/STANBOL-222?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13046862#comment-13046862
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Rupert Westenthaler commented on STANBOL-222:
---------------------------------------------
see http://markmail.org/thread/jbsvj23mtyqe726z for details and how to
re-formulate queries to improve query performance.
> Timeout exception from LOD remote endpoints when performing queries with the
> Entity Hub.
> ----------------------------------------------------------------------------------------
>
> Key: STANBOL-222
> URL: https://issues.apache.org/jira/browse/STANBOL-222
> Project: Stanbol
> Issue Type: Bug
> Components: Entity Hub
> Reporter: Andrea Nuzzolese
>
> The sparql constructs serialized by the Entity Hub that is used for querying
> remote LOD endpoints contain OPTIONAL patterns that require too much time to
> be evaluated.
> An example is the following
> CONSTRUCT { ... }
> WHERE {
> { {?id <http://www.w3.org/2002/07/owl#sameAs>
> <http://www4.wiwiss.fu-berlin.de/factbook/resource/United_States> }}
> { OPTIONAL { ?id <http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
> ?v_1 . } }
> { OPTIONAL { ?id <http://www.w3.org/2000/01/rdf-schema#label> ?v_2 . }
> }
> }
> ...
> The sparql engine tries to satisfy the optional clauses in the whole graph
> ignoring the first condition ?id <http://www.w3.org/2002/07/owl#sameAs>
> <http://www4.wiwiss.fu-berlin.de/factbook/resource/United_States>
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