/**
Copyright (C) SYSTAP, LLC DBA Blazegraph 2006-2016. All rights reserved.
Contact:
SYSTAP, LLC DBA Blazegraph
2501 Calvert ST NW #106
Washington, DC 20008
licenses@blazegraph.com
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/*
* Created on Aug 28, 2015
*/
package com.bigdata.rdf.sparql.ast.explainhints;
import com.bigdata.bop.BOp;
/**
* Explain hint indicating a MINUS expression that is unsatisfiable, i.e. does
* not have any effect at all. This happens if the left- and right-hand side
* of the minus have no variables in common. In such cases, the minus is
* optimized away, and there's most likely a problem in the query.
*
* @author <a href="ms@metaphacts.com">Michael Schmidt</a>
* @version $Id$
*/
public class UnsatisfiableMinusExplainHint extends ExplainHint {
private static final String EXPLAIN_HINT_TYPE = "Unsatisfiable Minus";
private static final String EXPLAIN_HINT_DESCRIPTION =
"The referenced AST node has been eliminated, because the MINUS " +
"expression that it represents has no effect. The reason is that " +
"the left-hand side expressiona and the minus expression have no " +
"shared variables. You may consider using FILTER NOT EXISTS as an " +
"alternative, see section http://www.w3.org/TR/2013/REC-sparql11-query-"
+ "20130321/#neg-notexists-minus in the SPARQL 1.1 standard.";
public UnsatisfiableMinusExplainHint(final BOp explainHintASTBase) {
super(
EXPLAIN_HINT_DESCRIPTION,
EXPLAIN_HINT_TYPE,
ExplainHintCategory.CORRECTNESS,
ExplainHintSeverity.MODERATE,
explainHintASTBase);
}
}