About: VirtTipsAndTricksQueryOptimizerASSUME

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Date Created	2017-06-13 05:47:39.944277(xsd:dateTime)
Date Modified	2017-06-13 05:47:39.944277(xsd:dateTime)
label	VirtTipsAndTricksQueryOptimizerASSUME
maker	WebDAV System Administrator owiki
Title	VirtTipsAndTricksQueryOptimizerASSUME
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content	%META:TOPICPARENT{name="VirtTipsAndTricksGuide"}% ---+How can I use the Virtuoso specific query optimizer hint ASSUME? <code>ASSUME</code> is a Virtuoso specific query optimizer hint for letting know the optimizer that the expression X is always true and the optimizer should work as such where you have ASSUME, while not triggering any SQL code generation for checking whether X is true (since it is ASSUMED to be true). Thus, in the example below, it is <b>ASSUMED</b> that <code>?id</code> is an IRI, so there's not need for any further type checking further down in the query-optimizer's processing workflow. ---++Usage Example: <verbatim> SELECT * WHERE { ?s1 <id> ?id ; geo:lat ?lat ; geo:long ?long . GRAPH ?rdf_view_g { ?s2 <id> ?id ; rdfs:label ?label } . ASSUME (isIRI (?id)) } </verbatim> ---++Related * [[VirtTipsAndTricksGuide][Virtuoso Tips and Tricks Collection]] * [[http://docs.openlinksw.com/virtuoso/rdfsparql.html][Virtuoso Documentation]] * [[VirtSPARQLOptGuideEx1][Optimizing query performance using bif functions Example]]
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atom:title	VirtTipsAndTricksQueryOptimizerASSUME
links to	http://docs.openlinksw.com/virtuoso/rdfsparql.html VirtTipsAndTricksGuide VirtSPARQLOptGuideEx1
atom:source	owiki's Wiki
atom:author	WebDAV System Administrator
atom:published	2017-06-13T05:47:39Z
atom:updated	2017-06-13T05:47:39Z
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