| 1 | /* |
| 2 | |
| 3 | Derby - Class org.apache.derby.impl.store.access.sort.Scan |
| 4 | |
| 5 | Copyright 1997, 2004 The Apache Software Foundation or its licensors, as applicable. |
| 6 | |
| 7 | Licensed under the Apache License, Version 2.0 (the "License"); |
| 8 | you may not use this file except in compliance with the License. |
| 9 | You may obtain a copy of the License at |
| 10 | |
| 11 | http://www.apache.org/licenses/LICENSE-2.0 |
| 12 | |
| 13 | Unless required by applicable law or agreed to in writing, software |
| 14 | distributed under the License is distributed on an "AS IS" BASIS, |
| 15 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 16 | See the License for the specific language governing permissions and |
| 17 | limitations under the License. |
| 18 | |
| 19 | */ |
| 20 | |
| 21 | package org.apache.derby.impl.store.access.sort; |
| 22 | |
| 23 | import org.apache.derby.iapi.reference.SQLState; |
| 24 | |
| 25 | import org.apache.derby.iapi.store.access.BackingStoreHashtable; |
| 26 | import org.apache.derby.iapi.services.io.FormatableBitSet; |
| 27 | import org.apache.derby.iapi.services.i18n.MessageService; |
| 28 | |
| 29 | import org.apache.derby.iapi.services.io.Storable; |
| 30 | |
| 31 | import org.apache.derby.iapi.types.Orderable; |
| 32 | import org.apache.derby.iapi.types.RowLocation; |
| 33 | |
| 34 | import org.apache.derby.iapi.error.StandardException; |
| 35 | |
| 36 | import org.apache.derby.iapi.store.access.conglomerate.Conglomerate; |
| 37 | import org.apache.derby.iapi.store.access.conglomerate.ScanManager; |
| 38 | |
| 39 | import org.apache.derby.iapi.store.access.Qualifier; |
| 40 | import org.apache.derby.iapi.store.access.ScanController; |
| 41 | import org.apache.derby.iapi.store.access.ScanInfo; |
| 42 | |
| 43 | import org.apache.derby.iapi.store.raw.Page; |
| 44 | |
| 45 | import org.apache.derby.iapi.types.DataValueDescriptor; |
| 46 | |
| 47 | import java.util.Properties; |
| 48 | |
| 49 | /** |
| 50 | |
| 51 | Abstract base class for all sort classes which return rows from the |
| 52 | sort. Subclasses must implement fetch, next, and close. |
| 53 | |
| 54 | **/ |
| 55 | |
| 56 | public abstract class Scan implements ScanManager, ScanInfo |
| 57 | { |
| 58 | /* |
| 59 | * Methods of ScanController |
| 60 | */ |
| 61 | |
| 62 | /** |
| 63 | * A call to allow client to indicate that current row does not qualify. |
| 64 | * <p> |
| 65 | * Indicates to the ScanController that the current row does not |
| 66 | * qualify for the scan. If the isolation level of the scan allows, |
| 67 | * this may result in the scan releasing the lock on this row. |
| 68 | * <p> |
| 69 | * Note that some scan implimentations may not support releasing locks on |
| 70 | * non-qualifying rows, or may delay releasing the lock until sometime |
| 71 | * later in the scan (ie. it may be necessary to keep the lock until |
| 72 | * either the scan is repositioned on the next row or page). |
| 73 | * <p> |
| 74 | * This call should only be made while the scan is positioned on a current |
| 75 | * valid row. |
| 76 | * <p> |
| 77 | * This call does not make sense for sort scans. |
| 78 | * |
| 79 | * @exception StandardException Standard exception policy. |
| 80 | **/ |
| 81 | public void didNotQualify() |
| 82 | throws StandardException |
| 83 | { |
| 84 | } |
| 85 | |
| 86 | /** |
| 87 | * Fetch the next N rows from the table. |
| 88 | * <p> |
| 89 | * Currently unimplemented for sorts. |
| 90 | * <p> |
| 91 | **/ |
| 92 | public int fetchNextGroup( |
| 93 | DataValueDescriptor[][] row_array, |
| 94 | RowLocation[] rowloc_array) |
| 95 | throws StandardException |
| 96 | { |
| 97 | throw StandardException.newException( |
| 98 | SQLState.SORT_IMPROPER_SCAN_METHOD); |
| 99 | } |
| 100 | |
| 101 | public int fetchNextGroup( |
| 102 | DataValueDescriptor[][] row_array, |
| 103 | RowLocation[] old_rowloc_array, |
| 104 | RowLocation[] new_rowloc_array) |
| 105 | throws StandardException |
| 106 | { |
| 107 | throw StandardException.newException( |
| 108 | SQLState.SORT_IMPROPER_SCAN_METHOD); |
| 109 | } |
| 110 | |
| 111 | |
| 112 | /** |
| 113 | * Insert all rows that qualify for the current scan into the input |
| 114 | * Hash table. |
| 115 | * <p> |
| 116 | * Currently unimplemented for sorts. |
| 117 | * <p> |
| 118 | **/ |
| 119 | public void fetchSet( |
| 120 | long max_rowcnt, |
| 121 | int[] key_column_numbers, |
| 122 | BackingStoreHashtable hash_table) |
| 123 | throws StandardException |
| 124 | { |
| 125 | throw StandardException.newException( |
| 126 | SQLState.SORT_IMPROPER_SCAN_METHOD); |
| 127 | } |
| 128 | |
| 129 | /** |
| 130 | Returns true if the current position of the scan still qualifies |
| 131 | under the set of qualifiers passed to the openScan(). |
| 132 | @see ScanController#doesCurrentPositionQualify |
| 133 | **/ |
| 134 | public boolean doesCurrentPositionQualify() |
| 135 | throws StandardException |
| 136 | { |
| 137 | return true; |
| 138 | } |
| 139 | |
| 140 | /** |
| 141 | Fetch the location of the current position in the scan. |
| 142 | @see ScanController#fetchLocation |
| 143 | **/ |
| 144 | public void fetchLocation(RowLocation templateLocation) |
| 145 | throws StandardException |
| 146 | { |
| 147 | throw StandardException.newException( |
| 148 | SQLState.SORT_IMPROPER_SCAN_METHOD); |
| 149 | } |
| 150 | |
| 151 | /** |
| 152 | * Return ScanInfo object which describes performance of scan. |
| 153 | * <p> |
| 154 | * Return ScanInfo object which contains information about the current |
| 155 | * scan. |
| 156 | * <p> |
| 157 | * Currently the ScanInfo does not have any performance data. |
| 158 | * |
| 159 | * @see ScanInfo |
| 160 | * |
| 161 | * @return The ScanInfo object which contains info about current scan. |
| 162 | * |
| 163 | * @exception StandardException Standard exception policy. |
| 164 | **/ |
| 165 | public ScanInfo getScanInfo() |
| 166 | throws StandardException |
| 167 | { |
| 168 | return(this); |
| 169 | } |
| 170 | |
| 171 | /** |
| 172 | * Get the total estimated number of rows in the container. |
| 173 | * <p> |
| 174 | * The number is a rough estimate and may be grossly off. In general |
| 175 | * the server will cache the row count and then occasionally write |
| 176 | * the count unlogged to a backing store. If the system happens to |
| 177 | * shutdown before the store gets a chance to update the row count it |
| 178 | * may wander from reality. |
| 179 | * <p> |
| 180 | * This call is currently only supported on Heap conglomerates, it |
| 181 | * will throw an exception if called on btree conglomerates. |
| 182 | * |
| 183 | * @return The total estimated number of rows in the conglomerate. |
| 184 | * |
| 185 | * @exception StandardException Standard exception policy. |
| 186 | **/ |
| 187 | public long getEstimatedRowCount() |
| 188 | throws StandardException |
| 189 | { |
| 190 | throw StandardException.newException( |
| 191 | SQLState.SORT_IMPROPER_SCAN_METHOD); |
| 192 | } |
| 193 | |
| 194 | /** |
| 195 | * Set the total estimated number of rows in the container. |
| 196 | * <p> |
| 197 | * Often, after a scan, the client of RawStore has a much better estimate |
| 198 | * of the number of rows in the container than what store has. For |
| 199 | * instance if we implement some sort of update statistics command, or |
| 200 | * just after a create index a complete scan will have been done of the |
| 201 | * table. In this case this interface allows the client to set the |
| 202 | * estimated row count for the container, and store will use that number |
| 203 | * for all future references. |
| 204 | * <p> |
| 205 | * This call is currently only supported on Heap conglomerates, it |
| 206 | * will throw an exception if called on btree conglomerates. |
| 207 | * |
| 208 | * @param count the estimated number of rows in the container. |
| 209 | * |
| 210 | * @exception StandardException Standard exception policy. |
| 211 | **/ |
| 212 | public void setEstimatedRowCount(long count) |
| 213 | throws StandardException |
| 214 | { |
| 215 | throw StandardException.newException( |
| 216 | SQLState.SORT_IMPROPER_SCAN_METHOD); |
| 217 | } |
| 218 | |
| 219 | /** |
| 220 | Returns true if the current position of the scan is at a |
| 221 | deleted row. |
| 222 | @see ScanController#isCurrentPositionDeleted |
| 223 | **/ |
| 224 | public boolean isCurrentPositionDeleted() |
| 225 | throws StandardException |
| 226 | { |
| 227 | throw StandardException.newException( |
| 228 | SQLState.SORT_IMPROPER_SCAN_METHOD); |
| 229 | } |
| 230 | |
| 231 | /** |
| 232 | * Return whether this is a keyed conglomerate. |
| 233 | * <p> |
| 234 | * |
| 235 | * @return whether this is a keyed conglomerate. |
| 236 | **/ |
| 237 | public boolean isKeyed() |
| 238 | { |
| 239 | return(false); |
| 240 | } |
| 241 | |
| 242 | /** |
| 243 | * Return whether this scan is table locked. |
| 244 | * |
| 245 | * @return whether this is table locked. |
| 246 | **/ |
| 247 | public boolean isTableLocked() |
| 248 | { |
| 249 | return(true); |
| 250 | } |
| 251 | |
| 252 | /** |
| 253 | Delete the row at the current position of the scan. |
| 254 | @see ScanController#delete |
| 255 | **/ |
| 256 | public boolean delete() |
| 257 | throws StandardException |
| 258 | { |
| 259 | throw StandardException.newException( |
| 260 | SQLState.SORT_IMPROPER_SCAN_METHOD); |
| 261 | } |
| 262 | |
| 263 | /** |
| 264 | Reposition the current scan. |
| 265 | @see ScanController#reopenScan |
| 266 | **/ |
| 267 | public void reopenScan( |
| 268 | DataValueDescriptor[] startKeyValue, |
| 269 | int startSearchOperator, |
| 270 | Qualifier qualifier[][], |
| 271 | DataValueDescriptor[] stopKeyValue, |
| 272 | int stopSearchOperator) |
| 273 | throws StandardException |
| 274 | { |
| 275 | throw StandardException.newException( |
| 276 | SQLState.SORT_IMPROPER_SCAN_METHOD); |
| 277 | } |
| 278 | |
| 279 | /** |
| 280 | Reposition the current scan. This call is semantically the same as if |
| 281 | the current scan had been closed and a openScan() had been called instead. |
| 282 | The scan is reopened against the same conglomerate, and the scan |
| 283 | is reopened with the same "scan column list", "hold" and "forUpdate" |
| 284 | parameters passed in the original openScan. |
| 285 | |
| 286 | @exception StandardException Standard exception policy. |
| 287 | **/ |
| 288 | public void reopenScanByRowLocation( |
| 289 | RowLocation startRowLocation, |
| 290 | Qualifier qualifier[][]) |
| 291 | throws StandardException |
| 292 | { |
| 293 | throw StandardException.newException( |
| 294 | SQLState.SORT_IMPROPER_SCAN_METHOD); |
| 295 | } |
| 296 | |
| 297 | /** |
| 298 | Replace the entire row at the current position of the scan. |
| 299 | @see ScanController#replace |
| 300 | **/ |
| 301 | public boolean replace( |
| 302 | DataValueDescriptor[] val, |
| 303 | FormatableBitSet validColumns) |
| 304 | throws StandardException |
| 305 | { |
| 306 | throw StandardException.newException( |
| 307 | SQLState.SORT_IMPROPER_SCAN_METHOD); |
| 308 | } |
| 309 | |
| 310 | /** |
| 311 | Return a row location object of the correct type to be |
| 312 | used in calls to fetchLocation. |
| 313 | @see ScanController#newRowLocationTemplate |
| 314 | **/ |
| 315 | public RowLocation newRowLocationTemplate() |
| 316 | throws StandardException |
| 317 | { |
| 318 | throw StandardException.newException( |
| 319 | SQLState.SORT_IMPROPER_SCAN_METHOD); |
| 320 | } |
| 321 | |
| 322 | /** |
| 323 | *@see ScanController#positionAtRowLocation |
| 324 | */ |
| 325 | public boolean positionAtRowLocation(RowLocation rl) |
| 326 | throws StandardException |
| 327 | { |
| 328 | throw StandardException.newException( |
| 329 | SQLState.SORT_IMPROPER_SCAN_METHOD); |
| 330 | } |
| 331 | |
| 332 | /* |
| 333 | ** Methods of ScanManager |
| 334 | */ |
| 335 | |
| 336 | /** |
| 337 | * Do work necessary to maintain the current position in the scan. |
| 338 | * <p> |
| 339 | * The latched page in the conglomerate "congomid" is changing, do |
| 340 | * whatever is necessary to maintain the current position of the scan. |
| 341 | * For some conglomerates this may be a no-op. |
| 342 | * <p> |
| 343 | * |
| 344 | * @param conglom Conglomerate object of the conglomerate being changed. |
| 345 | * @param page Page in the conglomerate being changed. |
| 346 | * |
| 347 | * @exception StandardException Standard exception policy. |
| 348 | **/ |
| 349 | public void savePosition(Conglomerate conglom, Page page) |
| 350 | throws StandardException |
| 351 | { |
| 352 | // RESOLVE (mikem), under the current implementation all scans within |
| 353 | // a transaction are called rather than just the ones with the right |
| 354 | // conglomid. For now just have sort scans ignore the call. |
| 355 | |
| 356 | return; |
| 357 | } |
| 358 | |
| 359 | /* |
| 360 | * Methods of ScanInfo |
| 361 | */ |
| 362 | |
| 363 | /** |
| 364 | * Return all information gathered about the scan. |
| 365 | * <p> |
| 366 | * This routine returns a list of properties which contains all information |
| 367 | * gathered about the scan. If a Property is passed in, then that property |
| 368 | * list is appeneded to, otherwise a new property object is created and |
| 369 | * returned. |
| 370 | * <p> |
| 371 | * Currently sort scans doesn't track any information. |
| 372 | * |
| 373 | * @param prop Property list to fill in. |
| 374 | * |
| 375 | * @exception StandardException Standard exception policy. |
| 376 | **/ |
| 377 | public Properties getAllScanInfo(Properties prop) |
| 378 | throws StandardException |
| 379 | { |
| 380 | if (prop == null) |
| 381 | prop = new Properties(); |
| 382 | |
| 383 | prop.put( |
| 384 | MessageService.getTextMessage(SQLState.STORE_RTS_SCAN_TYPE), |
| 385 | MessageService.getTextMessage(SQLState.STORE_RTS_SORT)); |
| 386 | |
| 387 | return(prop); |
| 388 | } |
| 389 | } |