com.bigdata.relation.IMutableRelation Maven / Gradle / Ivy
/*
Copyright (C) SYSTAP, LLC DBA Blazegraph 2006-2016. All rights reserved.
Contact:
SYSTAP, LLC DBA Blazegraph
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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 Jun 24, 2008
*/
package com.bigdata.relation;
import com.bigdata.btree.BTree;
import com.bigdata.journal.AbstractJournal;
import com.bigdata.striterator.IChunkedOrderedIterator;
/**
* A mutable {@link IRelation}. The relation must maintain any secondary
* indices under mutation.
*
* The methods declared by this interface return a "mutation count" - the
* mutation count MUST be exact and MUST NOT count overwrites that do not change
* the state of the tuple (the same key and value). The mutation counts are used
* to determine the fixed point for closure of a rule set. If they do not follow
* this contract then the closure operation will not terminate!
*
* If fact, it is MUCH more efficient if an implementation avoids the overwrite
* of an element with identical data. All index writes (including overwrites)
* add data to the {@link AbstractJournal} backing the mutable {@link BTree}
* absorbing writes for an index. An "overwrite" thus incurs more IO and will
* trigger overflow for the journal earlier than if overwrite were avoided. In
* contrast, while you have a lock on the mutable index you can test for a
* pre-existing key and compare the serialized byte[] values with relatively
* little cost (zero additional IO).
*
* @author Bryan Thompson
* @version $Id$
* @param
* The generic type of the [E]lements of the relation.
*/
public interface IMutableRelation extends IRelation, IMutableResource> {
/**
* Write elements on the relation.
*
* @param itr
* An iterator visiting the elements to be written.
*
* @return The #of elements that were actually written on the relation.
*/
public long insert(IChunkedOrderedIterator itr);
/**
* Remove elements from the relation.
*
* @param itr
* An iterator visiting the elements to be removed. Existing
* elements in the relation having a key equal to the key formed
* from the visited elements will be removed from the relation.
*
* @return The #of elements that were actually removed from the relation.
*/
public long delete(IChunkedOrderedIterator itr);
}