Examples of org.apache.hadoop.hbase.HRegion

org.apache.hadoop.hbase.HRegion
HRegion stores data for a certain region of a table. It stores all columns for each row. A given table consists of one or more HRegions.
We maintain multiple HStores for a single HRegion.
An HStore is a set of rows with some column data; together, they make up all the data for the rows.
Each HRegion has a 'startKey' and 'endKey'.
The first is inclusive, the second is exclusive (except for the final region) The endKey of region 0 is the same as startKey for region 1 (if it exists). The startKey for the first region is null. The endKey for the final region is null.
The HStores have no locking built-in. All row-level locking and row-level atomicity is provided by the HRegion.
An HRegion is defined by its table and its key extent.
It consists of at least one HStore. The number of HStores should be configurable, so that data which is accessed together is stored in the same HStore. Right now, we approximate that by building a single HStore for each column family. (This config info will be communicated via the tabledesc.) The HTableDescriptor contains metainfo about the HRegion's table. regionName is a unique identifier for this HRegion. (startKey, endKey] defines the keyspace for this HRegion.

   * regions, it will be some time before someone has enough data in HBase to
   * split the meta region and even less likely that a merge of two meta
   * regions will be needed, but it is included for completeness.
   */
  private void mergeTwoMetaRegions() throws IOException {
    HRegion rootRegion = utils.getRootRegion();
    HRegionInfo info1 = Writables.getHRegionInfoOrNull(
        rootRegion.get(region1, HConstants.COL_REGIONINFO));
    HRegionInfo info2 = Writables.getHRegionInfoOrNull(
        rootRegion.get(region2, HConstants.COL_REGIONINFO));
    HRegion merged = merge(info1, rootRegion, info2, rootRegion); 
    LOG.info("Adding " + merged.getRegionInfo() + " to " +
        rootRegion.getRegionInfo());
    HRegion.addRegionToMETA(rootRegion, merged);
    merged.close();
  }

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    HRegionInfo meta2 = listener.getMeta2();
    if (meta2 == null) {
      throw new IOException("Could not find meta region for " + region2);
    }


    HRegion metaRegion1 = utils.getMetaRegion(meta1);
    HRegionInfo info1 = Writables.getHRegionInfoOrNull(
        metaRegion1.get(region1, HConstants.COL_REGIONINFO));




    HRegion metaRegion2 = null;
    if (meta1.getRegionName().equals(meta2.getRegionName())) {
      metaRegion2 = metaRegion1;
    } else {
      metaRegion2 = utils.getMetaRegion(meta2);
    }
    HRegionInfo info2 = Writables.getHRegionInfoOrNull(
        metaRegion2.get(region2, HConstants.COL_REGIONINFO));


    HRegion merged = merge(info1, metaRegion1, info2, metaRegion2);


    // Now find the meta region which will contain the newly merged region


    listener = new MetaScannerListener(merged.getRegionName(), null);
    utils.scanRootRegion(listener);
    HRegionInfo mergedInfo = listener.getMeta1();
    if (mergedInfo == null) {
      throw new IOException("Could not find meta region for " +
          merged.getRegionName());
    }
    HRegion mergeMeta = null;
    if (mergedInfo.getRegionName().equals(meta1.getRegionName())) {
      mergeMeta = metaRegion1;
    } else if (mergedInfo.getRegionName().equals(meta2.getRegionName())) {
      mergeMeta = metaRegion2;
    } else {
      mergeMeta = utils.getMetaRegion(mergedInfo);
    }
    LOG.info("Adding " + merged.getRegionInfo() + " to " +
        mergeMeta.getRegionInfo());


    HRegion.addRegionToMETA(mergeMeta, merged);
    merged.close();
  }

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    }
    if (info2 == null) {
      throw new IOException("Cound not find " + region2 + " in " +
          meta2.getRegionName());
    }
    HRegion merged = null;
    HLog log = utils.getLog();
    HRegion region1 =
      HRegion.openHRegion(info1, this.rootdir, log, this.conf);
    try {
      HRegion region2 =
        HRegion.openHRegion(info2, this.rootdir, log, this.conf);
      try {
        merged = HRegion.merge(region1, region2);
      } finally {
        if (!region2.isClosed()) {
          region2.close();
        }
      }
    } finally {
      if (!region1.isClosed()) {
        region1.close();

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   */
  public HRegion getMetaRegion(HRegionInfo metaInfo) throws IOException {
    if (!initialized) {
      throw new IllegalStateException("Must call initialize method first.");
    }
    HRegion meta = metaRegions.get(metaInfo.getRegionName());
    if (meta == null) {
      meta = openMetaRegion(metaInfo);
      metaRegions.put(metaInfo.getRegionName(), meta);
    }
    return meta;

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      throw new IllegalStateException("Must call initialize method first.");
    }
    
    // Open meta region so we can scan it


    HRegion metaRegion = openMetaRegion(metaRegionInfo);


    HScannerInterface metaScanner = metaRegion.getScanner(
        HConstants.COL_REGIONINFO_ARRAY, HConstants.EMPTY_START_ROW,
        HConstants.LATEST_TIMESTAMP, null);


    try {
      HStoreKey key = new HStoreKey();

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        this.rootdir, this.log, this.conf);
    this.rootRegion.compactStores();
  }
  
  private HRegion openMetaRegion(HRegionInfo metaInfo) throws IOException {
    HRegion meta =
      HRegion.openHRegion(metaInfo, this.rootdir, this.log, this.conf);
    meta.compactStores();
    return meta;
  }

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