/**
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 Oct 1, 2010
*/
package com.bigdata.btree;
/**
* Interface used to report out some statistics about a B+Tree. These statistics
* may be used in combination with a disk cost model to predict the cost
* (latency) associated with a variety of operations on the B+Tree. All values
* reported by this interface are tracked explicitly by the
* {@link AbstractBTree} and do not require DISK IO.
*
* @author <a href="mailto:thompsonbry@users.sourceforge.net">Bryan Thompson</a>
* @version $Id$
*/
public interface IBTreeStatistics {
/**
* The branching factor for the btree.
*/
int getBranchingFactor();
/**
* The height of the btree. The height is the #of levels minus one. A btree
* with only a root leaf has <code>height := 0</code>. A btree with a
* root node and one level of leaves under it has <code>height := 1</code>.
* Note that all leaves of a btree are at the same height (this is what is
* means for the btree to be "balanced"). Also note that the height only
* changes when we split or join the root node (a btree maintains balance by
* growing and shrinking in levels from the top rather than the leaves).
*/
int getHeight();
/**
* The #of non-leaf nodes in the {@link AbstractBTree}. This is zero (0)
* for a new btree.
*/
long getNodeCount();
/**
* The #of leaf nodes in the {@link AbstractBTree}. This is one (1) for a
* new btree.
*/
long getLeafCount();
/**
* The #of entries (aka tuples) in the {@link AbstractBTree}. This is zero
* (0) for a new B+Tree. When the B+Tree supports delete markers, this value
* also includes tuples which have been marked as deleted.
*/
long getEntryCount();
/**
* Computes and returns the utilization of the tree. The utilization figures
* do not factor in the space requirements of nodes and leaves.
*/
IBTreeUtilizationReport getUtilization();
}