1 /* 2 * 3 * Licensed to the Apache Software Foundation (ASF) under one 4 * or more contributor license agreements. See the NOTICE file 5 * distributed with this work for additional information 6 * regarding copyright ownership. The ASF licenses this file 7 * to you under the Apache License, Version 2.0 (the 8 * "License"); you may not use this file except in compliance 9 * with the License. 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 package org.apache.hadoop.hbase.client; 21 22 import java.io.IOException; 23 import java.util.ArrayList; 24 import java.util.Arrays; 25 import java.util.HashMap; 26 import java.util.List; 27 import java.util.Map; 28 import java.util.NavigableSet; 29 import java.util.TreeMap; 30 import java.util.TreeSet; 31 32 import org.apache.commons.logging.Log; 33 import org.apache.commons.logging.LogFactory; 34 import org.apache.hadoop.hbase.classification.InterfaceAudience; 35 import org.apache.hadoop.hbase.classification.InterfaceStability; 36 import org.apache.hadoop.hbase.HConstants; 37 import org.apache.hadoop.hbase.client.metrics.ScanMetrics; 38 import org.apache.hadoop.hbase.filter.Filter; 39 import org.apache.hadoop.hbase.filter.IncompatibleFilterException; 40 import org.apache.hadoop.hbase.io.TimeRange; 41 import org.apache.hadoop.hbase.protobuf.ProtobufUtil; 42 import org.apache.hadoop.hbase.security.access.Permission; 43 import org.apache.hadoop.hbase.security.visibility.Authorizations; 44 import org.apache.hadoop.hbase.util.Bytes; 45 46 /** 47 * Used to perform Scan operations. 48 * <p> 49 * All operations are identical to {@link Get} with the exception of 50 * instantiation. Rather than specifying a single row, an optional startRow 51 * and stopRow may be defined. If rows are not specified, the Scanner will 52 * iterate over all rows. 53 * <p> 54 * To scan everything for each row, instantiate a Scan object. 55 * <p> 56 * To modify scanner caching for just this scan, use {@link #setCaching(int) setCaching}. 57 * If caching is NOT set, we will use the caching value of the hosting {@link Table}. 58 * In addition to row caching, it is possible to specify a 59 * maximum result size, using {@link #setMaxResultSize(long)}. When both are used, 60 * single server requests are limited by either number of rows or maximum result size, whichever 61 * limit comes first. 62 * <p> 63 * To further define the scope of what to get when scanning, perform additional 64 * methods as outlined below. 65 * <p> 66 * To get all columns from specific families, execute {@link #addFamily(byte[]) addFamily} 67 * for each family to retrieve. 68 * <p> 69 * To get specific columns, execute {@link #addColumn(byte[], byte[]) addColumn} 70 * for each column to retrieve. 71 * <p> 72 * To only retrieve columns within a specific range of version timestamps, 73 * execute {@link #setTimeRange(long, long) setTimeRange}. 74 * <p> 75 * To only retrieve columns with a specific timestamp, execute 76 * {@link #setTimeStamp(long) setTimestamp}. 77 * <p> 78 * To limit the number of versions of each column to be returned, execute 79 * {@link #setMaxVersions(int) setMaxVersions}. 80 * <p> 81 * To limit the maximum number of values returned for each call to next(), 82 * execute {@link #setBatch(int) setBatch}. 83 * <p> 84 * To add a filter, execute {@link #setFilter(org.apache.hadoop.hbase.filter.Filter) setFilter}. 85 * <p> 86 * Expert: To explicitly disable server-side block caching for this scan, 87 * execute {@link #setCacheBlocks(boolean)}. 88 * <p><em>Note:</em> Usage alters Scan instances. Internally, attributes are updated as the Scan 89 * runs and if enabled, metrics accumulate in the Scan instance. Be aware this is the case when 90 * you go to clone a Scan instance or if you go to reuse a created Scan instance; safer is create 91 * a Scan instance per usage. 92 */ 93 @InterfaceAudience.Public 94 @InterfaceStability.Stable 95 public class Scan extends Query { 96 private static final Log LOG = LogFactory.getLog(Scan.class); 97 98 private static final String RAW_ATTR = "_raw_"; 99 100 private byte [] startRow = HConstants.EMPTY_START_ROW; 101 private byte [] stopRow = HConstants.EMPTY_END_ROW; 102 private int maxVersions = 1; 103 private int batch = -1; 104 105 /** 106 * Partial {@link Result}s are {@link Result}s must be combined to form a complete {@link Result}. 107 * The {@link Result}s had to be returned in fragments (i.e. as partials) because the size of the 108 * cells in the row exceeded max result size on the server. Typically partial results will be 109 * combined client side into complete results before being delivered to the caller. However, if 110 * this flag is set, the caller is indicating that they do not mind seeing partial results (i.e. 111 * they understand that the results returned from the Scanner may only represent part of a 112 * particular row). In such a case, any attempt to combine the partials into a complete result on 113 * the client side will be skipped, and the caller will be able to see the exact results returned 114 * from the server. 115 */ 116 private boolean allowPartialResults = false; 117 118 private int storeLimit = -1; 119 private int storeOffset = 0; 120 private boolean getScan; 121 122 /** 123 * @deprecated since 1.0.0. Use {@link #setScanMetricsEnabled(boolean)} 124 */ 125 // Make private or remove. 126 @Deprecated 127 static public final String SCAN_ATTRIBUTES_METRICS_ENABLE = "scan.attributes.metrics.enable"; 128 129 /** 130 * Use {@link #getScanMetrics()} 131 */ 132 // Make this private or remove. 133 @Deprecated 134 static public final String SCAN_ATTRIBUTES_METRICS_DATA = "scan.attributes.metrics.data"; 135 136 // If an application wants to use multiple scans over different tables each scan must 137 // define this attribute with the appropriate table name by calling 138 // scan.setAttribute(Scan.SCAN_ATTRIBUTES_TABLE_NAME, Bytes.toBytes(tableName)) 139 static public final String SCAN_ATTRIBUTES_TABLE_NAME = "scan.attributes.table.name"; 140 141 /** 142 * @deprecated without replacement 143 * This is now a no-op, SEEKs and SKIPs are optimizated automatically. 144 * Will be removed in 2.0+ 145 */ 146 @Deprecated 147 public static final String HINT_LOOKAHEAD = "_look_ahead_"; 148 149 /* 150 * -1 means no caching 151 */ 152 private int caching = -1; 153 private long maxResultSize = -1; 154 private boolean cacheBlocks = true; 155 private boolean reversed = false; 156 private TimeRange tr = new TimeRange(); 157 private Map<byte [], NavigableSet<byte []>> familyMap = 158 new TreeMap<byte [], NavigableSet<byte []>>(Bytes.BYTES_COMPARATOR); 159 private Boolean loadColumnFamiliesOnDemand = null; 160 161 /** 162 * Set it true for small scan to get better performance 163 * 164 * Small scan should use pread and big scan can use seek + read 165 * 166 * seek + read is fast but can cause two problem (1) resource contention (2) 167 * cause too much network io 168 * 169 * [89-fb] Using pread for non-compaction read request 170 * https://issues.apache.org/jira/browse/HBASE-7266 171 * 172 * On the other hand, if setting it true, we would do 173 * openScanner,next,closeScanner in one RPC call. It means the better 174 * performance for small scan. [HBASE-9488]. 175 * 176 * Generally, if the scan range is within one data block(64KB), it could be 177 * considered as a small scan. 178 */ 179 private boolean small = false; 180 181 /** 182 * Create a Scan operation across all rows. 183 */ 184 public Scan() {} 185 186 public Scan(byte [] startRow, Filter filter) { 187 this(startRow); 188 this.filter = filter; 189 } 190 191 /** 192 * Create a Scan operation starting at the specified row. 193 * <p> 194 * If the specified row does not exist, the Scanner will start from the 195 * next closest row after the specified row. 196 * @param startRow row to start scanner at or after 197 */ 198 public Scan(byte [] startRow) { 199 this.startRow = startRow; 200 } 201 202 /** 203 * Create a Scan operation for the range of rows specified. 204 * @param startRow row to start scanner at or after (inclusive) 205 * @param stopRow row to stop scanner before (exclusive) 206 */ 207 public Scan(byte [] startRow, byte [] stopRow) { 208 this.startRow = startRow; 209 this.stopRow = stopRow; 210 //if the startRow and stopRow both are empty, it is not a Get 211 this.getScan = isStartRowAndEqualsStopRow(); 212 } 213 214 /** 215 * Creates a new instance of this class while copying all values. 216 * 217 * @param scan The scan instance to copy from. 218 * @throws IOException When copying the values fails. 219 */ 220 public Scan(Scan scan) throws IOException { 221 startRow = scan.getStartRow(); 222 stopRow = scan.getStopRow(); 223 maxVersions = scan.getMaxVersions(); 224 batch = scan.getBatch(); 225 storeLimit = scan.getMaxResultsPerColumnFamily(); 226 storeOffset = scan.getRowOffsetPerColumnFamily(); 227 caching = scan.getCaching(); 228 maxResultSize = scan.getMaxResultSize(); 229 cacheBlocks = scan.getCacheBlocks(); 230 getScan = scan.isGetScan(); 231 filter = scan.getFilter(); // clone? 232 loadColumnFamiliesOnDemand = scan.getLoadColumnFamiliesOnDemandValue(); 233 consistency = scan.getConsistency(); 234 reversed = scan.isReversed(); 235 small = scan.isSmall(); 236 TimeRange ctr = scan.getTimeRange(); 237 tr = new TimeRange(ctr.getMin(), ctr.getMax()); 238 Map<byte[], NavigableSet<byte[]>> fams = scan.getFamilyMap(); 239 for (Map.Entry<byte[],NavigableSet<byte[]>> entry : fams.entrySet()) { 240 byte [] fam = entry.getKey(); 241 NavigableSet<byte[]> cols = entry.getValue(); 242 if (cols != null && cols.size() > 0) { 243 for (byte[] col : cols) { 244 addColumn(fam, col); 245 } 246 } else { 247 addFamily(fam); 248 } 249 } 250 for (Map.Entry<String, byte[]> attr : scan.getAttributesMap().entrySet()) { 251 setAttribute(attr.getKey(), attr.getValue()); 252 } 253 } 254 255 /** 256 * Builds a scan object with the same specs as get. 257 * @param get get to model scan after 258 */ 259 public Scan(Get get) { 260 this.startRow = get.getRow(); 261 this.stopRow = get.getRow(); 262 this.filter = get.getFilter(); 263 this.cacheBlocks = get.getCacheBlocks(); 264 this.maxVersions = get.getMaxVersions(); 265 this.storeLimit = get.getMaxResultsPerColumnFamily(); 266 this.storeOffset = get.getRowOffsetPerColumnFamily(); 267 this.tr = get.getTimeRange(); 268 this.familyMap = get.getFamilyMap(); 269 this.getScan = true; 270 this.consistency = get.getConsistency(); 271 this.setIsolationLevel(get.getIsolationLevel()); 272 for (Map.Entry<String, byte[]> attr : get.getAttributesMap().entrySet()) { 273 setAttribute(attr.getKey(), attr.getValue()); 274 } 275 } 276 277 public boolean isGetScan() { 278 return this.getScan || isStartRowAndEqualsStopRow(); 279 } 280 281 private boolean isStartRowAndEqualsStopRow() { 282 return this.startRow != null && this.startRow.length > 0 && 283 Bytes.equals(this.startRow, this.stopRow); 284 } 285 /** 286 * Get all columns from the specified family. 287 * <p> 288 * Overrides previous calls to addColumn for this family. 289 * @param family family name 290 * @return this 291 */ 292 public Scan addFamily(byte [] family) { 293 familyMap.remove(family); 294 familyMap.put(family, null); 295 return this; 296 } 297 298 /** 299 * Get the column from the specified family with the specified qualifier. 300 * <p> 301 * Overrides previous calls to addFamily for this family. 302 * @param family family name 303 * @param qualifier column qualifier 304 * @return this 305 */ 306 public Scan addColumn(byte [] family, byte [] qualifier) { 307 NavigableSet<byte []> set = familyMap.get(family); 308 if(set == null) { 309 set = new TreeSet<byte []>(Bytes.BYTES_COMPARATOR); 310 } 311 if (qualifier == null) { 312 qualifier = HConstants.EMPTY_BYTE_ARRAY; 313 } 314 set.add(qualifier); 315 familyMap.put(family, set); 316 return this; 317 } 318 319 /** 320 * Get versions of columns only within the specified timestamp range, 321 * [minStamp, maxStamp). Note, default maximum versions to return is 1. If 322 * your time range spans more than one version and you want all versions 323 * returned, up the number of versions beyond the default. 324 * @param minStamp minimum timestamp value, inclusive 325 * @param maxStamp maximum timestamp value, exclusive 326 * @throws IOException if invalid time range 327 * @see #setMaxVersions() 328 * @see #setMaxVersions(int) 329 * @return this 330 */ 331 public Scan setTimeRange(long minStamp, long maxStamp) 332 throws IOException { 333 tr = new TimeRange(minStamp, maxStamp); 334 return this; 335 } 336 337 /** 338 * Get versions of columns with the specified timestamp. Note, default maximum 339 * versions to return is 1. If your time range spans more than one version 340 * and you want all versions returned, up the number of versions beyond the 341 * defaut. 342 * @param timestamp version timestamp 343 * @see #setMaxVersions() 344 * @see #setMaxVersions(int) 345 * @return this 346 */ 347 public Scan setTimeStamp(long timestamp) 348 throws IOException { 349 try { 350 tr = new TimeRange(timestamp, timestamp+1); 351 } catch(IOException e) { 352 // This should never happen, unless integer overflow or something extremely wrong... 353 LOG.error("TimeRange failed, likely caused by integer overflow. ", e); 354 throw e; 355 } 356 return this; 357 } 358 359 /** 360 * Set the start row of the scan. 361 * @param startRow row to start scan on (inclusive) 362 * Note: In order to make startRow exclusive add a trailing 0 byte 363 * @return this 364 */ 365 public Scan setStartRow(byte [] startRow) { 366 this.startRow = startRow; 367 return this; 368 } 369 370 /** 371 * Set the stop row. 372 * @param stopRow row to end at (exclusive) 373 * <p><b>Note:</b> In order to make stopRow inclusive add a trailing 0 byte</p> 374 * <p><b>Note:</b> When doing a filter for a rowKey <u>Prefix</u> 375 * use {@link #setRowPrefixFilter(byte[])}. 376 * The 'trailing 0' will not yield the desired result.</p> 377 * @return this 378 */ 379 public Scan setStopRow(byte [] stopRow) { 380 this.stopRow = stopRow; 381 return this; 382 } 383 384 /** 385 * <p>Set a filter (using stopRow and startRow) so the result set only contains rows where the 386 * rowKey starts with the specified prefix.</p> 387 * <p>This is a utility method that converts the desired rowPrefix into the appropriate values 388 * for the startRow and stopRow to achieve the desired result.</p> 389 * <p>This can safely be used in combination with setFilter.</p> 390 * <p><b>NOTE: Doing a {@link #setStartRow(byte[])} and/or {@link #setStopRow(byte[])} 391 * after this method will yield undefined results.</b></p> 392 * @param rowPrefix the prefix all rows must start with. (Set <i>null</i> to remove the filter.) 393 * @return this 394 */ 395 public Scan setRowPrefixFilter(byte[] rowPrefix) { 396 if (rowPrefix == null) { 397 setStartRow(HConstants.EMPTY_START_ROW); 398 setStopRow(HConstants.EMPTY_END_ROW); 399 } else { 400 this.setStartRow(rowPrefix); 401 this.setStopRow(calculateTheClosestNextRowKeyForPrefix(rowPrefix)); 402 } 403 return this; 404 } 405 406 /** 407 * <p>When scanning for a prefix the scan should stop immediately after the the last row that 408 * has the specified prefix. This method calculates the closest next rowKey immediately following 409 * the given rowKeyPrefix.</p> 410 * <p><b>IMPORTANT: This converts a rowKey<u>Prefix</u> into a rowKey</b>.</p> 411 * <p>If the prefix is an 'ASCII' string put into a byte[] then this is easy because you can 412 * simply increment the last byte of the array. 413 * But if your application uses real binary rowids you may run into the scenario that your 414 * prefix is something like:</p> 415 * <b>{ 0x12, 0x23, 0xFF, 0xFF }</b><br/> 416 * Then this stopRow needs to be fed into the actual scan<br/> 417 * <b>{ 0x12, 0x24 }</b> (Notice that it is shorter now)<br/> 418 * This method calculates the correct stop row value for this usecase. 419 * 420 * @param rowKeyPrefix the rowKey<u>Prefix</u>. 421 * @return the closest next rowKey immediately following the given rowKeyPrefix. 422 */ 423 private byte[] calculateTheClosestNextRowKeyForPrefix(byte[] rowKeyPrefix) { 424 // Essentially we are treating it like an 'unsigned very very long' and doing +1 manually. 425 // Search for the place where the trailing 0xFFs start 426 int offset = rowKeyPrefix.length; 427 while (offset > 0) { 428 if (rowKeyPrefix[offset - 1] != (byte) 0xFF) { 429 break; 430 } 431 offset--; 432 } 433 434 if (offset == 0) { 435 // We got an 0xFFFF... (only FFs) stopRow value which is 436 // the last possible prefix before the end of the table. 437 // So set it to stop at the 'end of the table' 438 return HConstants.EMPTY_END_ROW; 439 } 440 441 // Copy the right length of the original 442 byte[] newStopRow = Arrays.copyOfRange(rowKeyPrefix, 0, offset); 443 // And increment the last one 444 newStopRow[newStopRow.length - 1]++; 445 return newStopRow; 446 } 447 448 /** 449 * Get all available versions. 450 * @return this 451 */ 452 public Scan setMaxVersions() { 453 this.maxVersions = Integer.MAX_VALUE; 454 return this; 455 } 456 457 /** 458 * Get up to the specified number of versions of each column. 459 * @param maxVersions maximum versions for each column 460 * @return this 461 */ 462 public Scan setMaxVersions(int maxVersions) { 463 this.maxVersions = maxVersions; 464 return this; 465 } 466 467 /** 468 * Set the maximum number of values to return for each call to next() 469 * @param batch the maximum number of values 470 */ 471 public Scan setBatch(int batch) { 472 if (this.hasFilter() && this.filter.hasFilterRow()) { 473 throw new IncompatibleFilterException( 474 "Cannot set batch on a scan using a filter" + 475 " that returns true for filter.hasFilterRow"); 476 } 477 this.batch = batch; 478 return this; 479 } 480 481 /** 482 * Set the maximum number of values to return per row per Column Family 483 * @param limit the maximum number of values returned / row / CF 484 */ 485 public Scan setMaxResultsPerColumnFamily(int limit) { 486 this.storeLimit = limit; 487 return this; 488 } 489 490 /** 491 * Set offset for the row per Column Family. 492 * @param offset is the number of kvs that will be skipped. 493 */ 494 public Scan setRowOffsetPerColumnFamily(int offset) { 495 this.storeOffset = offset; 496 return this; 497 } 498 499 /** 500 * Set the number of rows for caching that will be passed to scanners. 501 * If not set, the Configuration setting {@link HConstants#HBASE_CLIENT_SCANNER_CACHING} will 502 * apply. 503 * Higher caching values will enable faster scanners but will use more memory. 504 * @param caching the number of rows for caching 505 */ 506 public Scan setCaching(int caching) { 507 this.caching = caching; 508 return this; 509 } 510 511 /** 512 * @return the maximum result size in bytes. See {@link #setMaxResultSize(long)} 513 */ 514 public long getMaxResultSize() { 515 return maxResultSize; 516 } 517 518 /** 519 * Set the maximum result size. The default is -1; this means that no specific 520 * maximum result size will be set for this scan, and the global configured 521 * value will be used instead. (Defaults to unlimited). 522 * 523 * @param maxResultSize The maximum result size in bytes. 524 */ 525 public Scan setMaxResultSize(long maxResultSize) { 526 this.maxResultSize = maxResultSize; 527 return this; 528 } 529 530 @Override 531 public Scan setFilter(Filter filter) { 532 super.setFilter(filter); 533 return this; 534 } 535 536 /** 537 * Setting the familyMap 538 * @param familyMap map of family to qualifier 539 * @return this 540 */ 541 public Scan setFamilyMap(Map<byte [], NavigableSet<byte []>> familyMap) { 542 this.familyMap = familyMap; 543 return this; 544 } 545 546 /** 547 * Getting the familyMap 548 * @return familyMap 549 */ 550 public Map<byte [], NavigableSet<byte []>> getFamilyMap() { 551 return this.familyMap; 552 } 553 554 /** 555 * @return the number of families in familyMap 556 */ 557 public int numFamilies() { 558 if(hasFamilies()) { 559 return this.familyMap.size(); 560 } 561 return 0; 562 } 563 564 /** 565 * @return true if familyMap is non empty, false otherwise 566 */ 567 public boolean hasFamilies() { 568 return !this.familyMap.isEmpty(); 569 } 570 571 /** 572 * @return the keys of the familyMap 573 */ 574 public byte[][] getFamilies() { 575 if(hasFamilies()) { 576 return this.familyMap.keySet().toArray(new byte[0][0]); 577 } 578 return null; 579 } 580 581 /** 582 * @return the startrow 583 */ 584 public byte [] getStartRow() { 585 return this.startRow; 586 } 587 588 /** 589 * @return the stoprow 590 */ 591 public byte [] getStopRow() { 592 return this.stopRow; 593 } 594 595 /** 596 * @return the max number of versions to fetch 597 */ 598 public int getMaxVersions() { 599 return this.maxVersions; 600 } 601 602 /** 603 * @return maximum number of values to return for a single call to next() 604 */ 605 public int getBatch() { 606 return this.batch; 607 } 608 609 /** 610 * @return maximum number of values to return per row per CF 611 */ 612 public int getMaxResultsPerColumnFamily() { 613 return this.storeLimit; 614 } 615 616 /** 617 * Method for retrieving the scan's offset per row per column 618 * family (#kvs to be skipped) 619 * @return row offset 620 */ 621 public int getRowOffsetPerColumnFamily() { 622 return this.storeOffset; 623 } 624 625 /** 626 * @return caching the number of rows fetched when calling next on a scanner 627 */ 628 public int getCaching() { 629 return this.caching; 630 } 631 632 /** 633 * @return TimeRange 634 */ 635 public TimeRange getTimeRange() { 636 return this.tr; 637 } 638 639 /** 640 * @return RowFilter 641 */ 642 @Override 643 public Filter getFilter() { 644 return filter; 645 } 646 647 /** 648 * @return true is a filter has been specified, false if not 649 */ 650 public boolean hasFilter() { 651 return filter != null; 652 } 653 654 /** 655 * Set whether blocks should be cached for this Scan. 656 * <p> 657 * This is true by default. When true, default settings of the table and 658 * family are used (this will never override caching blocks if the block 659 * cache is disabled for that family or entirely). 660 * 661 * @param cacheBlocks if false, default settings are overridden and blocks 662 * will not be cached 663 */ 664 public Scan setCacheBlocks(boolean cacheBlocks) { 665 this.cacheBlocks = cacheBlocks; 666 return this; 667 } 668 669 /** 670 * Get whether blocks should be cached for this Scan. 671 * @return true if default caching should be used, false if blocks should not 672 * be cached 673 */ 674 public boolean getCacheBlocks() { 675 return cacheBlocks; 676 } 677 678 /** 679 * Set whether this scan is a reversed one 680 * <p> 681 * This is false by default which means forward(normal) scan. 682 * 683 * @param reversed if true, scan will be backward order 684 * @return this 685 */ 686 public Scan setReversed(boolean reversed) { 687 this.reversed = reversed; 688 return this; 689 } 690 691 /** 692 * Get whether this scan is a reversed one. 693 * @return true if backward scan, false if forward(default) scan 694 */ 695 public boolean isReversed() { 696 return reversed; 697 } 698 699 /** 700 * Setting whether the caller wants to see the partial results that may be returned from the 701 * server. By default this value is false and the complete results will be assembled client side 702 * before being delivered to the caller. 703 * @param allowPartialResults 704 * @return this 705 */ 706 public Scan setAllowPartialResults(final boolean allowPartialResults) { 707 this.allowPartialResults = allowPartialResults; 708 return this; 709 } 710 711 /** 712 * @return true when the constructor of this scan understands that the results they will see may 713 * only represent a partial portion of a row. The entire row would be retrieved by 714 * subsequent calls to {@link ResultScanner#next()} 715 */ 716 public boolean getAllowPartialResults() { 717 return allowPartialResults; 718 } 719 720 /** 721 * Set the value indicating whether loading CFs on demand should be allowed (cluster 722 * default is false). On-demand CF loading doesn't load column families until necessary, e.g. 723 * if you filter on one column, the other column family data will be loaded only for the rows 724 * that are included in result, not all rows like in normal case. 725 * With column-specific filters, like SingleColumnValueFilter w/filterIfMissing == true, 726 * this can deliver huge perf gains when there's a cf with lots of data; however, it can 727 * also lead to some inconsistent results, as follows: 728 * - if someone does a concurrent update to both column families in question you may get a row 729 * that never existed, e.g. for { rowKey = 5, { cat_videos => 1 }, { video => "my cat" } } 730 * someone puts rowKey 5 with { cat_videos => 0 }, { video => "my dog" }, concurrent scan 731 * filtering on "cat_videos == 1" can get { rowKey = 5, { cat_videos => 1 }, 732 * { video => "my dog" } }. 733 * - if there's a concurrent split and you have more than 2 column families, some rows may be 734 * missing some column families. 735 */ 736 public Scan setLoadColumnFamiliesOnDemand(boolean value) { 737 this.loadColumnFamiliesOnDemand = value; 738 return this; 739 } 740 741 /** 742 * Get the raw loadColumnFamiliesOnDemand setting; if it's not set, can be null. 743 */ 744 public Boolean getLoadColumnFamiliesOnDemandValue() { 745 return this.loadColumnFamiliesOnDemand; 746 } 747 748 /** 749 * Get the logical value indicating whether on-demand CF loading should be allowed. 750 */ 751 public boolean doLoadColumnFamiliesOnDemand() { 752 return (this.loadColumnFamiliesOnDemand != null) 753 && this.loadColumnFamiliesOnDemand.booleanValue(); 754 } 755 756 /** 757 * Compile the table and column family (i.e. schema) information 758 * into a String. Useful for parsing and aggregation by debugging, 759 * logging, and administration tools. 760 * @return Map 761 */ 762 @Override 763 public Map<String, Object> getFingerprint() { 764 Map<String, Object> map = new HashMap<String, Object>(); 765 List<String> families = new ArrayList<String>(); 766 if(this.familyMap.size() == 0) { 767 map.put("families", "ALL"); 768 return map; 769 } else { 770 map.put("families", families); 771 } 772 for (Map.Entry<byte [], NavigableSet<byte[]>> entry : 773 this.familyMap.entrySet()) { 774 families.add(Bytes.toStringBinary(entry.getKey())); 775 } 776 return map; 777 } 778 779 /** 780 * Compile the details beyond the scope of getFingerprint (row, columns, 781 * timestamps, etc.) into a Map along with the fingerprinted information. 782 * Useful for debugging, logging, and administration tools. 783 * @param maxCols a limit on the number of columns output prior to truncation 784 * @return Map 785 */ 786 @Override 787 public Map<String, Object> toMap(int maxCols) { 788 // start with the fingerpring map and build on top of it 789 Map<String, Object> map = getFingerprint(); 790 // map from families to column list replaces fingerprint's list of families 791 Map<String, List<String>> familyColumns = 792 new HashMap<String, List<String>>(); 793 map.put("families", familyColumns); 794 // add scalar information first 795 map.put("startRow", Bytes.toStringBinary(this.startRow)); 796 map.put("stopRow", Bytes.toStringBinary(this.stopRow)); 797 map.put("maxVersions", this.maxVersions); 798 map.put("batch", this.batch); 799 map.put("caching", this.caching); 800 map.put("maxResultSize", this.maxResultSize); 801 map.put("cacheBlocks", this.cacheBlocks); 802 map.put("loadColumnFamiliesOnDemand", this.loadColumnFamiliesOnDemand); 803 List<Long> timeRange = new ArrayList<Long>(); 804 timeRange.add(this.tr.getMin()); 805 timeRange.add(this.tr.getMax()); 806 map.put("timeRange", timeRange); 807 int colCount = 0; 808 // iterate through affected families and list out up to maxCols columns 809 for (Map.Entry<byte [], NavigableSet<byte[]>> entry : 810 this.familyMap.entrySet()) { 811 List<String> columns = new ArrayList<String>(); 812 familyColumns.put(Bytes.toStringBinary(entry.getKey()), columns); 813 if(entry.getValue() == null) { 814 colCount++; 815 --maxCols; 816 columns.add("ALL"); 817 } else { 818 colCount += entry.getValue().size(); 819 if (maxCols <= 0) { 820 continue; 821 } 822 for (byte [] column : entry.getValue()) { 823 if (--maxCols <= 0) { 824 continue; 825 } 826 columns.add(Bytes.toStringBinary(column)); 827 } 828 } 829 } 830 map.put("totalColumns", colCount); 831 if (this.filter != null) { 832 map.put("filter", this.filter.toString()); 833 } 834 // add the id if set 835 if (getId() != null) { 836 map.put("id", getId()); 837 } 838 return map; 839 } 840 841 /** 842 * Enable/disable "raw" mode for this scan. 843 * If "raw" is enabled the scan will return all 844 * delete marker and deleted rows that have not 845 * been collected, yet. 846 * This is mostly useful for Scan on column families 847 * that have KEEP_DELETED_ROWS enabled. 848 * It is an error to specify any column when "raw" is set. 849 * @param raw True/False to enable/disable "raw" mode. 850 */ 851 public Scan setRaw(boolean raw) { 852 setAttribute(RAW_ATTR, Bytes.toBytes(raw)); 853 return this; 854 } 855 856 /** 857 * @return True if this Scan is in "raw" mode. 858 */ 859 public boolean isRaw() { 860 byte[] attr = getAttribute(RAW_ATTR); 861 return attr == null ? false : Bytes.toBoolean(attr); 862 } 863 864 865 866 /** 867 * Set whether this scan is a small scan 868 * <p> 869 * Small scan should use pread and big scan can use seek + read 870 * 871 * seek + read is fast but can cause two problem (1) resource contention (2) 872 * cause too much network io 873 * 874 * [89-fb] Using pread for non-compaction read request 875 * https://issues.apache.org/jira/browse/HBASE-7266 876 * 877 * On the other hand, if setting it true, we would do 878 * openScanner,next,closeScanner in one RPC call. It means the better 879 * performance for small scan. [HBASE-9488]. 880 * 881 * Generally, if the scan range is within one data block(64KB), it could be 882 * considered as a small scan. 883 * 884 * @param small 885 */ 886 public Scan setSmall(boolean small) { 887 this.small = small; 888 return this; 889 } 890 891 /** 892 * Get whether this scan is a small scan 893 * @return true if small scan 894 */ 895 public boolean isSmall() { 896 return small; 897 } 898 899 @Override 900 public Scan setAttribute(String name, byte[] value) { 901 return (Scan) super.setAttribute(name, value); 902 } 903 904 @Override 905 public Scan setId(String id) { 906 return (Scan) super.setId(id); 907 } 908 909 @Override 910 public Scan setAuthorizations(Authorizations authorizations) { 911 return (Scan) super.setAuthorizations(authorizations); 912 } 913 914 @Override 915 public Scan setACL(Map<String, Permission> perms) { 916 return (Scan) super.setACL(perms); 917 } 918 919 @Override 920 public Scan setACL(String user, Permission perms) { 921 return (Scan) super.setACL(user, perms); 922 } 923 924 @Override 925 public Scan setConsistency(Consistency consistency) { 926 return (Scan) super.setConsistency(consistency); 927 } 928 929 @Override 930 public Scan setReplicaId(int Id) { 931 return (Scan) super.setReplicaId(Id); 932 } 933 934 @Override 935 public Scan setIsolationLevel(IsolationLevel level) { 936 return (Scan) super.setIsolationLevel(level); 937 } 938 939 /** 940 * Utility that creates a Scan that will do a small scan in reverse from passed row 941 * looking for next closest row. 942 * @param row 943 * @param family 944 * @return An instance of Scan primed with passed <code>row</code> and <code>family</code> to 945 * scan in reverse for one row only. 946 */ 947 static Scan createGetClosestRowOrBeforeReverseScan(byte[] row) { 948 // Below does not work if you add in family; need to add the family qualifier that is highest 949 // possible family qualifier. Do we have such a notion? Would have to be magic. 950 Scan scan = new Scan(row); 951 scan.setSmall(true); 952 scan.setReversed(true); 953 scan.setCaching(1); 954 return scan; 955 } 956 957 /** 958 * Enable collection of {@link ScanMetrics}. For advanced users. 959 * @param enabled Set to true to enable accumulating scan metrics 960 */ 961 public Scan setScanMetricsEnabled(final boolean enabled) { 962 setAttribute(Scan.SCAN_ATTRIBUTES_METRICS_ENABLE, Bytes.toBytes(Boolean.valueOf(enabled))); 963 return this; 964 } 965 966 /** 967 * @return True if collection of scan metrics is enabled. For advanced users. 968 */ 969 public boolean isScanMetricsEnabled() { 970 byte[] attr = getAttribute(Scan.SCAN_ATTRIBUTES_METRICS_ENABLE); 971 return attr == null ? false : Bytes.toBoolean(attr); 972 } 973 974 /** 975 * @return Metrics on this Scan, if metrics were enabled. 976 * @see #setScanMetricsEnabled(boolean) 977 */ 978 public ScanMetrics getScanMetrics() { 979 byte [] bytes = getAttribute(Scan.SCAN_ATTRIBUTES_METRICS_DATA); 980 if (bytes == null) return null; 981 return ProtobufUtil.toScanMetrics(bytes); 982 } 983 }