com.bigdata.rdf.spo
Class DistinctMultiTermAdvancer

java.lang.Object
  cutthecrap.utils.striterators.FilterBase
      com.bigdata.btree.filter.Advancer<SPO>
          com.bigdata.rdf.spo.DistinctMultiTermAdvancer

All Implemented Interfaces:

ITupleFilter<SPO>, IFilter, IPropertySet, Serializable, Cloneable

public class DistinctMultiTermAdvancer
extends Advancer<SPO>

This was cloned from the DistinctTermAdvancer. It supports an efficient scan of the distinct term identifiers that appear in the first position(s) of the keys for the statement index corresponding to the specified IKeyOrder. For example, using SPOKeyOrder.POS will give you the term identifiers for the distinct predicates actually in use within statements in the SPORelation.

Note: This class only offers additional functionality over the DistinctTermAdvancer for a quad store. For example, consider a triple store with 2-bound on the SPOKeyOrder.SPO index. Since you are only going to visit the distinct Object values, the advancer will not "advance" over anything and you might as well use a normal IAccessPath or rangeIterator.

Version:

$Id: DistinctMultiTermAdvancer.java 2886 2010-05-19 19:16:49Z mroycsi $

Author:

Bryan Thompson

See Also:

DistinctTermAdvancer, Serialized Form

TODO:

Unit tests?

Field Summary

Fields inherited from class com.bigdata.btree.filter.Advancer

log, src

Constructor Summary

DistinctMultiTermAdvancer(int arity, int boundEntries)

Method Summary

protected void

advance(ITuple<SPO> tuple) Offers an opportunity to advance the source ITupleCursor to a new key using {@link ITupleCursor#seek(byte[]).

Methods inherited from class com.bigdata.btree.filter.Advancer

filterOnce, init

Methods inherited from class cutthecrap.utils.striterators.FilterBase

addFilter, filter, getProperty, getRequiredProperty, setProperty, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface cutthecrap.utils.striterators.IFilter

filter

Methods inherited from interface cutthecrap.utils.striterators.IPropertySet

getProperty

Constructor Detail

DistinctMultiTermAdvancer

public DistinctMultiTermAdvancer(int arity,
                                 int boundEntries)

Method Detail

advance

protected void advance(ITuple<SPO> tuple)

Description copied from class: Advancer

Offers an opportunity to advance the source ITupleCursor to a new key using {@link ITupleCursor#seek(byte[]).

Specified by:

advance in class Advancer<SPO>

Parameters:

tuple - The current value.