Examples of org.apache.hadoop.hbase.io.hfile.HFileScanner

Package org.apache.hadoop.hbase.io.hfile

Examples of org.apache.hadoop.hbase.io.hfile.HFileScanner

org.apache.hadoop.hbase.io.hfile.HFileScanner
A scanner allows you to position yourself within a HFile and scan through it. It allows you to reposition yourself as well.
A scanner doesn't always have a key/value that it is pointing to when it is first created and before {@link #seekTo()}/ {@link #seekTo(byte[])} are called.In this case, {@link #getKey()}/ {@link #getValue()} returns null. At mostother times, a key and value will be available. The general pattern is that you position the Scanner using the seekTo variants and then getKey and getValue.

                                        CacheConfig cacheConfig)
            throws IOException {
      final HalfStoreFileReader halfreader = new HalfStoreFileReader(fs, p,
              cacheConfig, bottom, DataBlockEncoding.NONE);
      halfreader.loadFileInfo();
      final HFileScanner scanner = halfreader.getScanner(false, false);
      scanner.seekBefore(seekBefore.getKey());
      return scanner.getKeyValue();
  }

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      doTestOfScanAndReseek(Path p, FileSystem fs, Reference bottom, CacheConfig cacheConf)
          throws IOException {
    final IndexHalfStoreFileReader halfreader =
        new IndexHalfStoreFileReader(fs, p, cacheConf, bottom, DataBlockEncoding.NONE);
    halfreader.loadFileInfo();
    final HFileScanner scanner = halfreader.getScanner(false, false);
    KeyValue getseekTorowKey3 = getSeekToRowKey();
    scanner.seekTo(getseekTorowKey3.getBuffer(), 8, 17);
    boolean next = scanner.next();
    KeyValue keyValue = null;
    if (next) {
      keyValue = scanner.getKeyValue();
    }
    byte[] expectedRow = getExpected();
    byte[] actualRow = keyValue.getRow();
    Assert.assertArrayEquals(expectedRow, actualRow);
    halfreader.close(true);

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            + this.region);
      }


      if (verifyBulkLoads) {
        KeyValue prevKV = null;
        HFileScanner scanner = reader.getScanner(false, false, false);
        scanner.seekTo();
        do {
          KeyValue kv = scanner.getKeyValue();
          if (prevKV != null) {
            if (Bytes.compareTo(prevKV.getBuffer(), prevKV.getRowOffset(),
                prevKV.getRowLength(), kv.getBuffer(), kv.getRowOffset(),
                kv.getRowLength()) > 0) {
              throw new InvalidHFileException("Previous row is greater than"
                  + " current row: path=" + srcPath + " previous="
                  + Bytes.toStringBinary(prevKV.getKey()) + " current="
                  + Bytes.toStringBinary(kv.getKey()));
            }
            if (Bytes.compareTo(prevKV.getBuffer(), prevKV.getFamilyOffset(),
                prevKV.getFamilyLength(), kv.getBuffer(), kv.getFamilyOffset(),
                kv.getFamilyLength()) != 0) {
              throw new InvalidHFileException("Previous key had different"
                  + " family compared to current key: path=" + srcPath
                  + " previous=" + Bytes.toStringBinary(prevKV.getFamily())
                  + " current=" + Bytes.toStringBinary(kv.getFamily()));
            }
          }
          prevKV = kv;
        } while (scanner.next());
      }
    } finally {
      if (reader != null) reader.close();
    }
  }

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      // If the row we're looking for is past the end of file, set search key to
      // last key. TODO: Cache last and first key rather than make each time.
      firstOnRow = new KeyValue(lastKV.getRow(), HConstants.LATEST_TIMESTAMP);
    }
    // Get a scanner that caches blocks and that uses pread.
    HFileScanner scanner = r.getScanner(true, true, false);
    // Seek scanner.  If can't seek it, return.
    if (!seekToScanner(scanner, firstOnRow, firstKV)) return;
    // If we found candidate on firstOnRow, just return. THIS WILL NEVER HAPPEN!
    // Unlikely that there'll be an instance of actual first row in table.
    if (walkForwardInSingleRow(scanner, firstOnRow, state)) return;
    // If here, need to start backing up.
    while (scanner.seekBefore(firstOnRow.getBuffer(), firstOnRow.getKeyOffset(),
       firstOnRow.getKeyLength())) {
      KeyValue kv = scanner.getKeyValue();
      if (!state.isTargetTable(kv)) break;
      if (!state.isBetterCandidate(kv)) break;
      // Make new first on row.
      firstOnRow = new KeyValue(kv.getRow(), HConstants.LATEST_TIMESTAMP);
      // Seek scanner.  If can't seek it, break.

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      if (!state.isTargetTable(lastKV)) return;
      // If the row we're looking for is past the end of file, set search key to
      // last key. TODO: Cache last and first key rather than make each time.
      firstOnRow = new KeyValue(lastKV.getRow(), HConstants.LATEST_TIMESTAMP);
    }
    HFileScanner scanner = r.getScanner();
    // Seek scanner.  If can't seek it, return.
    if (!seekToScanner(scanner, firstOnRow, firstKV)) return;
    // If we found candidate on firstOnRow, just return. THIS WILL NEVER HAPPEN!
    // Unlikely that there'll be an instance of actual first row in table.
    if (walkForwardInSingleRow(scanner, firstOnRow, state)) return;
    // If here, need to start backing up.
    while (scanner.seekBefore(firstOnRow.getBuffer(), firstOnRow.getKeyOffset(),
       firstOnRow.getKeyLength())) {
      KeyValue kv = scanner.getKeyValue();
      if (!state.isTargetTable(kv)) break;
      if (!state.isBetterCandidate(kv)) break;
      // Make new first on row.
      firstOnRow = new KeyValue(kv.getRow(), HConstants.LATEST_TIMESTAMP);
      // Seek scanner.  If can't seek it, break.

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    return this.getScanner(true);
  }
  
  @Override
  public HFileScanner getScanner(boolean cacheBlocks) {
    final HFileScanner s = super.getScanner(cacheBlocks);
    return new HFileScanner() {
      final HFileScanner delegate = s;
      public boolean atEnd = false;


      public ByteBuffer getKey() {
        if (atEnd) return null;

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  @Override
  public byte[] getLastKey() {
    if (top) {
      return super.getLastKey(); 
    }
    HFileScanner scanner = getScanner();
    try {
      if (scanner.seekBefore(this.splitkey)) {
        return Bytes.toBytes(scanner.getKey());
      }
    } catch (IOException e) {
      LOG.warn("Failed seekBefore " + Bytes.toString(this.splitkey), e);
    }
    return null;

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      super(conf, fs, mf, totalRows);
    }


    @Override
    void doRow(int i) throws Exception {
      HFileScanner scanner = this.reader.getScanner();
      byte [] b = getRandomRow();
      scanner.seekTo(b);
      ByteBuffer k = scanner.getKey();
      PerformanceEvaluationCommons.assertKey(b, k);
      ByteBuffer v = scanner.getValue();
      PerformanceEvaluationCommons.assertValueSize(v.limit(), ROW_LENGTH);
    }

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      super(conf, fs, mf, totalRows/10);
    }


    @Override
    void doRow(int i) throws Exception {
      HFileScanner scanner = this.reader.getScanner();
      byte [] b = getRandomRow();
      if (scanner.seekTo(b) != 0) {
        System.out.println("Nonexistent row: " + new String(b));
        return;
      }
      ByteBuffer k = scanner.getKey();
      PerformanceEvaluationCommons.assertKey(b, k);
      // System.out.println("Found row: " + new String(b));
      for (int ii = 0; ii < 30; ii++) {
        if (!scanner.next()) {
          System.out.println("NOTHING FOLLOWS");
        }
        ByteBuffer v = scanner.getValue();
        PerformanceEvaluationCommons.assertValueSize(v.limit(), ROW_LENGTH);
      }
    }

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      super(conf, fs, mf, totalRows);
    }


    @Override
    void doRow(int i) throws Exception {
      HFileScanner scanner = this.reader.getScanner();
      scanner.seekTo(getGaussianRandomRowBytes());
      for (int ii = 0; ii < 30; ii++) {
        if (!scanner.next()) {
          System.out.println("NOTHING FOLLOWS");
        }
        scanner.getKey();
        scanner.getValue();
      }
    }

View Full Code Here

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org.apache.crunch.io.hbase.HFileReaderFactory

org.apache.hadoop.hbase.HFilePerformanceEvaluation$GaussianRandomReadBenchmark

org.apache.hadoop.hbase.HFilePerformanceEvaluation$UniformRandomReadBenchmark

org.apache.hadoop.hbase.HFilePerformanceEvaluation$UniformRandomSmallScan

org.apache.hadoop.hbase.index.io.IndexHalfStoreFileReader

org.apache.hadoop.hbase.index.io.TestIndexHalfStoreFileReader

org.apache.hadoop.hbase.index.mapreduce.IndexLoadIncrementalHFile

org.apache.hadoop.hbase.io.HalfHFileReader

org.apache.hadoop.hbase.io.HalfStoreFileReader

org.apache.hadoop.hbase.io.TestHalfStoreFileReader

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