| 1 | /* ============================================================= |
| 2 | * SmallSQL : a free Java DBMS library for the Java(tm) platform |
| 3 | * ============================================================= |
| 4 | * |
| 5 | * (C) Copyright 2004-2006, by Volker Berlin. |
| 6 | * |
| 7 | * Project Info: http://www.smallsql.de/ |
| 8 | * |
| 9 | * This library is free software; you can redistribute it and/or modify it |
| 10 | * under the terms of the GNU Lesser General Public License as published by |
| 11 | * the Free Software Foundation; either version 2.1 of the License, or |
| 12 | * (at your option) any later version. |
| 13 | * |
| 14 | * This library is distributed in the hope that it will be useful, but |
| 15 | * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY |
| 16 | * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public |
| 17 | * License for more details. |
| 18 | * |
| 19 | * You should have received a copy of the GNU Lesser General Public |
| 20 | * License along with this library; if not, write to the Free Software |
| 21 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, |
| 22 | * USA. |
| 23 | * |
| 24 | * [Java is a trademark or registered trademark of Sun Microsystems, Inc. |
| 25 | * in the United States and other countries.] |
| 26 | * |
| 27 | * --------------- |
| 28 | * IndexDescription.java |
| 29 | * --------------- |
| 30 | * Author: Volker Berlin |
| 31 | * |
| 32 | * Created on 19.04.2005 |
| 33 | */ |
| 34 | package smallsql.database; |
| 35 | |
| 36 | import java.io.File; |
| 37 | import java.io.RandomAccessFile; |
| 38 | import java.sql.SQLException; |
| 39 | |
| 40 | |
| 41 | |
| 42 | final class IndexDescription { |
| 43 | |
| 44 | static final int MAGIC_INDEX = 'S' << 24 | 'Q' << 16 | 'L' << 8 | 'I'; |
| 45 | static final int INDEX_VERSION = 1; |
| 46 | |
| 47 | private String name; |
| 48 | final private int constraintType; //PRIMARY, UNIQUE, FOREIGIN, INDEX |
| 49 | final private Strings columns; |
| 50 | private int[] matrix; |
| 51 | final private Expressions expressions; |
| 52 | private Index index; |
| 53 | |
| 54 | |
| 55 | /** |
| 56 | * |
| 57 | * @param constraintType one of SQLTokenizer.PRIMARY, SQLTokenizer.UNIQUE, SQLTokenizer.FOREIGN or SQLTokenizer.INDEX. |
| 58 | * @param columns the Expressions that build the index. For example one or more database columns. |
| 59 | */ |
| 60 | IndexDescription(int constraintType, Expressions expressions, Strings columns){ |
| 61 | this.constraintType = constraintType; |
| 62 | this.expressions = expressions; |
| 63 | this.columns = columns; |
| 64 | } |
| 65 | |
| 66 | |
| 67 | final void setName(String name){ |
| 68 | this.name = name; |
| 69 | } |
| 70 | |
| 71 | |
| 72 | final String getName(){ |
| 73 | return name; |
| 74 | } |
| 75 | |
| 76 | |
| 77 | final boolean isPrimary(){ |
| 78 | return constraintType == SQLTokenizer.PRIMARY; |
| 79 | } |
| 80 | |
| 81 | |
| 82 | final boolean isUnique(){ |
| 83 | return constraintType == SQLTokenizer.PRIMARY || constraintType == SQLTokenizer.UNIQUE; |
| 84 | } |
| 85 | |
| 86 | |
| 87 | final Strings getColumns(){ |
| 88 | return columns; |
| 89 | } |
| 90 | |
| 91 | |
| 92 | /** |
| 93 | * Descript how well the index match to the column list. |
| 94 | * @param strings a list of columns that should match |
| 95 | * @return Integer.MAX_VALUE does not match; 0 - 100% match |
| 96 | */ |
| 97 | final int matchFactor(Strings strings){ |
| 98 | if(strings.size() < columns.size()) |
| 99 | return Integer.MAX_VALUE; //does not map |
| 100 | |
| 101 | nextColumn: |
| 102 | for(int c=0; c<columns.size(); c++){ |
| 103 | String colName = columns.get(c); |
| 104 | for(int s=0; s<strings.size(); s++){ |
| 105 | if(colName.equalsIgnoreCase(strings.get(s)) ) |
| 106 | continue nextColumn; |
| 107 | } |
| 108 | return Integer.MAX_VALUE; //No Strin found for colName |
| 109 | } |
| 110 | return strings.size() - columns.size(); |
| 111 | } |
| 112 | |
| 113 | |
| 114 | /** |
| 115 | * Create a binding of the columns form this index to the columns of the table. |
| 116 | * @param database |
| 117 | * @param tableView |
| 118 | * @see IndexDescriptions#setTableView |
| 119 | */ |
| 120 | final void init(Database database, TableView tableView)/* throws Exception*/{ |
| 121 | int size = tableView.columns.size(); |
| 122 | matrix = new int[size]; |
| 123 | for(int i=0; i<matrix.length; i++){ |
| 124 | matrix[i] = -1; |
| 125 | } |
| 126 | |
| 127 | for(int i=0; i<columns.size(); i++){ |
| 128 | matrix[tableView.findColumnIdx(columns.get(i))] = i; |
| 129 | } |
| 130 | if(name == null){ |
| 131 | name = tableView.name + "_" + Long.toHexString(System.currentTimeMillis()) + Integer.toHexString(hashCode()); |
| 132 | } |
| 133 | |
| 134 | } |
| 135 | |
| 136 | |
| 137 | /** |
| 138 | * Create the index. A file for storing the index data is saved. |
| 139 | */ |
| 140 | final void create(Database database, TableView tableView) throws Exception{ |
| 141 | init( database, tableView ); |
| 142 | createFile( database ).close(); |
| 143 | } |
| 144 | |
| 145 | |
| 146 | static File getFile(Database database, String name) throws Exception{ |
| 147 | return new File( Utils.createIdxFileName( database, name ) ); |
| 148 | } |
| 149 | |
| 150 | |
| 151 | private RandomAccessFile createFile(Database database) throws Exception{ |
| 152 | File file = getFile( database, name ); |
| 153 | boolean ok = file.createNewFile(); |
| 154 | if(!ok) throw Utils.createSQLException("Index '" + name + "' allready exists."); |
| 155 | RandomAccessFile raFile = new RandomAccessFile( file, "rw" ); |
| 156 | writeMagic(raFile); |
| 157 | return raFile; |
| 158 | } |
| 159 | |
| 160 | |
| 161 | public void drop(Database database) throws Exception { |
| 162 | boolean ok = getFile( database, name).delete(); |
| 163 | if(!ok) throw Utils.createSQLException("Table '" + name + "' can't drop."); |
| 164 | } |
| 165 | |
| 166 | private final void writeMagic(RandomAccessFile raFile) throws Exception{ |
| 167 | raFile.writeInt(MAGIC_INDEX); |
| 168 | raFile.writeInt(INDEX_VERSION); |
| 169 | } |
| 170 | |
| 171 | |
| 172 | /** |
| 173 | * This is call if a single colum of the table is changed. |
| 174 | * @param columnIdx The column position in the table |
| 175 | * @param valueExpression the new value of the current row. |
| 176 | */ |
| 177 | final void writeExpression( int columnIdx, Expression valueExpression) { |
| 178 | int idx = matrix[columnIdx]; |
| 179 | if(idx >= 0) //set only if the column part of this index |
| 180 | expressions.set(idx, valueExpression); |
| 181 | } |
| 182 | |
| 183 | |
| 184 | /** |
| 185 | * This is call if the row is finsch written. |
| 186 | * @param con the connection for a later commit or rollback. |
| 187 | */ |
| 188 | final void writeFinsh(SSConnection con) { |
| 189 | //TODO |
| 190 | //index.addValues(expressions); |
| 191 | } |
| 192 | |
| 193 | |
| 194 | /** |
| 195 | * Save this IndexDescription in the Table definition. |
| 196 | */ |
| 197 | final void save(StoreImpl store) throws SQLException{ |
| 198 | store.writeInt(constraintType); |
| 199 | store.writeInt(columns.size()); |
| 200 | for(int c=0; c<columns.size(); c++){ |
| 201 | store.writeString( columns.get(c) ); |
| 202 | } |
| 203 | store.writeString(name); |
| 204 | } |
| 205 | |
| 206 | |
| 207 | /** |
| 208 | * Restore a IndexDescription from a saved Table. |
| 209 | */ |
| 210 | final static IndexDescription load(Database database, TableView tableView, StoreImpl store) throws SQLException{ |
| 211 | int constraintType = store.readInt(); |
| 212 | int count = store.readInt(); |
| 213 | Strings columns = new Strings(); |
| 214 | Expressions expressions = new Expressions(); |
| 215 | SQLParser sqlParser = new SQLParser(); |
| 216 | for(int c=0; c<count; c++){ |
| 217 | String column = store.readString(); |
| 218 | columns.add( column ); |
| 219 | expressions.add( sqlParser.parseExpression(column)); |
| 220 | } |
| 221 | IndexDescription indexDesc = new IndexDescription(constraintType, expressions, columns); |
| 222 | indexDesc.setName( store.readString() ); |
| 223 | indexDesc.init( database, tableView ); |
| 224 | return indexDesc; |
| 225 | } |
| 226 | |
| 227 | |
| 228 | } |