1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
|
package de.lmu.ifi.dbs.elki.index.tree.metrical.mtreevariants.mtree;
/*
This file is part of ELKI:
Environment for Developing KDD-Applications Supported by Index-Structures
Copyright (C) 2011
Ludwig-Maximilians-Universität München
Lehr- und Forschungseinheit für Datenbanksysteme
ELKI Development Team
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
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 Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
import de.lmu.ifi.dbs.elki.database.ids.DBID;
import de.lmu.ifi.dbs.elki.database.query.distance.DistanceQuery;
import de.lmu.ifi.dbs.elki.distance.distancefunction.DistanceFunction;
import de.lmu.ifi.dbs.elki.distance.distancevalue.Distance;
import de.lmu.ifi.dbs.elki.index.tree.metrical.mtreevariants.AbstractMTree;
import de.lmu.ifi.dbs.elki.index.tree.metrical.mtreevariants.MTreeDirectoryEntry;
import de.lmu.ifi.dbs.elki.index.tree.metrical.mtreevariants.MTreeEntry;
import de.lmu.ifi.dbs.elki.logging.Logging;
import de.lmu.ifi.dbs.elki.persistent.PageFile;
import de.lmu.ifi.dbs.elki.utilities.documentation.Description;
import de.lmu.ifi.dbs.elki.utilities.documentation.Reference;
import de.lmu.ifi.dbs.elki.utilities.documentation.Title;
/**
* MTree is a metrical index structure based on the concepts of the M-Tree.
* Apart from organizing the objects it also provides several methods to search
* for certain object in the structure. Persistence is not yet ensured.
*
* @author Elke Achtert
*
* @apiviz.has MTreeNode oneway - - contains
*
* @param <O> the type of DatabaseObject to be stored in the metrical index
* @param <D> the type of Distance used in the metrical index
*/
@Title("M-Tree")
@Description("Efficient Access Method for Similarity Search in Metric Spaces")
@Reference(authors = "P. Ciaccia, M. Patella, P. Zezula", title = "M-tree: An Efficient Access Method for Similarity Search in Metric Spaces", booktitle = "VLDB'97, Proceedings of 23rd International Conference on Very Large Data Bases, August 25-29, 1997, Athens, Greece", url = "http://www.vldb.org/conf/1997/P426.PDF")
public class MTree<O, D extends Distance<D>> extends AbstractMTree<O, D, MTreeNode<O, D>, MTreeEntry<D>> {
/**
* The logger for this class.
*/
private static final Logging logger = Logging.getLogger(MTree.class);
/**
* Constructor.
*
* @param pagefile Page file
* @param distanceQuery Distance query
* @param distanceFunction Distance function
*/
public MTree(PageFile<MTreeNode<O, D>> pagefile, DistanceQuery<O, D> distanceQuery, DistanceFunction<O, D> distanceFunction) {
super(pagefile, distanceQuery, distanceFunction);
}
/**
* Does nothing because no operations are necessary before inserting an entry.
*/
@Override
protected void preInsert(@SuppressWarnings("unused") MTreeEntry<D> entry) {
// do nothing
}
@Override
protected void initializeCapacities(MTreeEntry<D> exampleLeaf) {
int distanceSize = exampleLeaf.getParentDistance().externalizableSize();
// FIXME: simulate a proper feature size!
int featuresize = 0; // DatabaseUtil.dimensionality(relation);
// overhead = index(4), numEntries(4), id(4), isLeaf(0.125)
double overhead = 12.125;
if(getPageSize() - overhead < 0) {
throw new RuntimeException("Node size of " + getPageSize() + " Bytes is chosen too small!");
}
// dirCapacity = (pageSize - overhead) / (nodeID + objectID +
// coveringRadius + parentDistance) + 1
// dirCapacity = (int) (pageSize - overhead) / (4 + 4 + distanceSize +
// distanceSize) + 1;
// dirCapacity = (pageSize - overhead) / (nodeID + **object feature size** +
// coveringRadius + parentDistance) + 1
dirCapacity = (int) (getPageSize() - overhead) / (4 + featuresize + distanceSize + distanceSize) + 1;
if(dirCapacity <= 2) {
throw new RuntimeException("Node size of " + getPageSize() + " Bytes is chosen too small!");
}
if(dirCapacity < 10) {
logger.warning("Page size is choosen too small! Maximum number of entries " + "in a directory node = " + (dirCapacity - 1));
}
// leafCapacity = (pageSize - overhead) / (objectID + parentDistance) +
// 1
// leafCapacity = (int) (pageSize - overhead) / (4 + distanceSize) + 1;
// leafCapacity = (pageSize - overhead) / (objectID + ** object size ** +
// parentDistance) +
// 1
leafCapacity = (int) (getPageSize() - overhead) / (4 + featuresize + distanceSize) + 1;
if(leafCapacity <= 1) {
throw new RuntimeException("Node size of " + getPageSize() + " Bytes is chosen too small!");
}
if(leafCapacity < 10) {
logger.warning("Page size is choosen too small! Maximum number of entries " + "in a leaf node = " + (leafCapacity - 1));
}
if(logger.isVerbose()) {
logger.verbose("Directory Capacity: " + (dirCapacity - 1) + "\nLeaf Capacity: " + (leafCapacity - 1));
}
}
/**
* @return a new MTreeDirectoryEntry representing the specified node
*/
@Override
protected MTreeEntry<D> createNewDirectoryEntry(MTreeNode<O, D> node, DBID routingObjectID, D parentDistance) {
return new MTreeDirectoryEntry<D>(routingObjectID, parentDistance, node.getPageID(), node.coveringRadius(routingObjectID, this));
}
/**
* @return a new MTreeDirectoryEntry by calling
* <code>new MTreeDirectoryEntry<D>(null, null, 0, null)</code>
*/
@Override
protected MTreeEntry<D> createRootEntry() {
return new MTreeDirectoryEntry<D>(null, null, 0, null);
}
/**
* @return a new MTreeNode which is a leaf node
*/
@Override
protected MTreeNode<O, D> createNewLeafNode() {
return new MTreeNode<O, D>(leafCapacity, true);
}
/**
* @return a new MTreeNode which is a directory node
*/
@Override
protected MTreeNode<O, D> createNewDirectoryNode() {
return new MTreeNode<O, D>(dirCapacity, false);
}
@Override
protected Logging getLogger() {
return logger;
}
}
|
