Examples of org.apache.hadoop.hbase.client.Scan

org.apache.hadoop.hbase.client.Scan
Used to perform Scan operations.
All operations are identical to {@link Get} with the exception ofinstantiation. Rather than specifying a single row, an optional startRow and stopRow may be defined. If rows are not specified, the Scanner will iterate over all rows.
To scan everything for each row, instantiate a Scan object.
To modify scanner caching for just this scan, use {@link #setCaching(int) setCaching}. If caching is NOT set, we will use the caching value of the hosting {@link HTable}. See {@link HTable#setScannerCaching(int)}.
To further define the scope of what to get when scanning, perform additional methods as outlined below.
To get all columns from specific families, execute {@link #addFamily(byte[]) addFamily}for each family to retrieve.
To get specific columns, execute {@link #addColumn(byte[],byte[]) addColumn}for each column to retrieve.
To only retrieve columns within a specific range of version timestamps, execute {@link #setTimeRange(long,long) setTimeRange}.
To only retrieve columns with a specific timestamp, execute {@link #setTimeStamp(long) setTimestamp}.
To limit the number of versions of each column to be returned, execute {@link #setMaxVersions(int) setMaxVersions}.
To limit the maximum number of values returned for each call to next(), execute {@link #setBatch(int) setBatch}.
To add a filter, execute {@link #setFilter(org.apache.hadoop.hbase.filter.Filter) setFilter}.
Expert: To explicitly disable server-side block caching for this scan, execute {@link #setCacheBlocks(boolean)}.

    public int scannerOpenTs(ByteBuffer tableName, ByteBuffer startRow,
        List<ByteBuffer> columns, long timestamp,
        Map<ByteBuffer, ByteBuffer> attributes) throws IOError, TException {
      try {
        HTable table = getTable(tableName);
        Scan scan = new Scan(getBytes(startRow));
        addAttributes(scan, attributes);
        scan.setTimeRange(Long.MIN_VALUE, timestamp);
        if (columns != null && columns.size() != 0) {
          for (ByteBuffer column : columns) {
            byte [][] famQf = KeyValue.parseColumn(getBytes(column));
            if(famQf.length == 1) {
              scan.addFamily(famQf[0]);
            } else {
              scan.addColumn(famQf[0], famQf[1]);
            }
          }
        }
        return addScanner(table.getScanner(scan));
      } catch (IOException e) {

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        ByteBuffer stopRow, List<ByteBuffer> columns, long timestamp,
        Map<ByteBuffer, ByteBuffer> attributes)
        throws IOError, TException {
      try {
        HTable table = getTable(tableName);
        Scan scan = new Scan(getBytes(startRow), getBytes(stopRow));
        addAttributes(scan, attributes);
        scan.setTimeRange(Long.MIN_VALUE, timestamp);
        if (columns != null && columns.size() != 0) {
          for (ByteBuffer column : columns) {
            byte [][] famQf = KeyValue.parseColumn(getBytes(column));
            if(famQf.length == 1) {
              scan.addFamily(famQf[0]);
            } else {
              scan.addColumn(famQf[0], famQf[1]);
            }
          }
        }
        scan.setTimeRange(Long.MIN_VALUE, timestamp);
        return addScanner(table.getScanner(scan));
      } catch (IOException e) {
        LOG.warn(e.getMessage(), e);
        throw new IOError(e.getMessage());
      }

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       if (coprocessorHost.preGet(get, results)) {
         return results;
       }
    }


    Scan scan = new Scan(get);


    RegionScanner scanner = null;
    try {
      scanner = getScanner(scan);
      scanner.next(results, SchemaMetrics.METRIC_GETSIZE);

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      region.initialize();
      if (majorCompact) {
        region.compactStores(true);
      } else {
        // Default behavior
        Scan scan = new Scan();
        // scan.addFamily(HConstants.CATALOG_FAMILY);
        RegionScanner scanner = region.getScanner(scan);
        try {
          List<KeyValue> kvs = new ArrayList<KeyValue>();
          boolean done = false;

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      region.put(p);


      Get get = new Get(row.getBytes());
      Filter filter = new ColumnCountGetFilter(100);
      get.setFilter(filter);
      Scan scan = new Scan(get);
      InternalScanner scanner = region.getScanner(scan);
      List<KeyValue> results = new ArrayList<KeyValue>();
      scanner.next(results);
      assertEquals(100, results.size());
    } finally {

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      Get get = new Get(row.getBytes());
      FilterList filterLst = new FilterList ();
      filterLst.addFilter( new ColumnCountGetFilter(100));
      get.setFilter(filterLst);
      Scan scan = new Scan(get);
      InternalScanner scanner = region.getScanner(scan);
      List<KeyValue> results = new ArrayList<KeyValue>();
      scanner.next(results);
      assertEquals(100, results.size());
    } finally {

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    Configuration c = new Configuration(this.conf);
    this.hbaseCluster = new MiniHBaseCluster(c, numMasters, numSlaves);
    // Don't leave here till we've done a successful scan of the .META.
    HTable t = new HTable(c, HConstants.META_TABLE_NAME);
    ResultScanner s = t.getScanner(new Scan());
    while (s.next() != null) {
      continue;
    }
    s.close();
    t.close();

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   */
  public void restartHBaseCluster(int servers) throws IOException, InterruptedException {
    this.hbaseCluster = new MiniHBaseCluster(this.conf, servers);
    // Don't leave here till we've done a successful scan of the .META.
    HTable t = new HTable(new Configuration(this.conf), HConstants.META_TABLE_NAME);
    ResultScanner s = t.getScanner(new Scan());
    while (s.next() != null) {
      // do nothing
    }
    LOG.info("HBase has been restarted");
    s.close();

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   * @return HTable to that new table
   * @throws IOException
   */
  public HTable truncateTable(byte [] tableName) throws IOException {
    HTable table = new HTable(getConfiguration(), tableName);
    Scan scan = new Scan();
    ResultScanner resScan = table.getScanner(scan);
    for(Result res : resScan) {
      Delete del = new Delete(res.getRow());
      table.delete(del);
    }

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  /**
   * Return the number of rows in the given table.
   */
  public int countRows(final HTable table) throws IOException {
    Scan scan = new Scan();
    ResultScanner results = table.getScanner(scan);
    int count = 0;
    for (@SuppressWarnings("unused") Result res : results) {
      count++;
    }

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