/**
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 Mar 10, 2012
*/
package com.bigdata.rdf.sparql.ast;
import com.bigdata.bop.BOp;
import com.bigdata.rdf.sparql.ast.optimizers.StaticOptimizer;
import com.bigdata.rdf.store.ITripleStore;
/**
* Interface for things which can be re-ordered by the static join
* optimizer. Currently limited to StatementPatternNodes and some
* instances of ArbitraryLengthPathNodes (those with a single statement pattern
* inside).
*/
public interface IReorderableNode extends IGroupMemberNode, IBindingProducerNode, BOp {
/**
* The decision about whether to re-order can no longer be made simply
* by examining the type - individual instances of a particular type
* may or may not be reorderable.
*/
boolean isReorderable();
/**
* Return the estimated cardinality - either the range count of a
* statement pattern or some computed estimated cardinality for a join
* group.
* @param opt This optimizer can be used to help work out the estimate
*/
long getEstimatedCardinality(StaticOptimizer opt);
}