org.apache.hadoop.hbase.util
Class MetaUtils

java.lang.Object
  org.apache.hadoop.hbase.util.MetaUtils

public class MetaUtils
extends java.lang.Object

Contains utility methods for manipulating HBase meta tables. Be sure to call shutdown() when done with this class so it closes resources opened during meta processing (ROOT, META, etc.). Be careful how you use this class. If used during migrations, be careful when using this class to check whether migration is needed.

Nested Class Summary

static interface

MetaUtils.ScannerListener Used by scanRootRegion and scanMetaRegion to call back the caller so it can process the data for a row.

Constructor Summary

MetaUtils()
Default constructor

MetaUtils(org.apache.hadoop.conf.Configuration conf)

Method Summary

void	addColumn(byte[] tableName, HColumnDescriptor hcd) Offline version of the online TableOperation, org.apache.hadoop.hbase.master.AddColumn.
static void	changeOnlineStatus(org.apache.hadoop.conf.Configuration c, byte[] row, boolean onlineOffline) Set a single region on/offline.
void	deleteColumn(byte[] tableName, byte[] columnFamily) Offline version of the online TableOperation, org.apache.hadoop.hbase.master.DeleteColumn.
HLog	getLog()
HRegion	getMetaRegion(HRegionInfo metaInfo) Open or return cached opened meta region
java.util.List<HRegionInfo>	getMETARows(byte[] tableName)
HRegion	getRootRegion()
void	scanMetaRegion(HRegionInfo metaRegionInfo, MetaUtils.ScannerListener listener) Scans a meta region.
void	scanMetaRegion(HRegion r, MetaUtils.ScannerListener listener) Scan the passed in metaregion m invoking the passed listener per row found.
void	scanRootRegion(MetaUtils.ScannerListener listener) Scans the root region.
void	shutdown() Closes catalog regions if open.
void	updateMETARegionInfo(HRegion r, HRegionInfo hri) Update COL_REGIONINFO in meta region r with HRegionInfo hri

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

MetaUtils

public MetaUtils()
          throws java.io.IOException

Default constructor

Throws:

java.io.IOException - e

MetaUtils

public MetaUtils(org.apache.hadoop.conf.Configuration conf)
          throws java.io.IOException

Parameters:

conf - Configuration

Throws:

java.io.IOException - e

Method Detail

getLog

public HLog getLog()
            throws java.io.IOException

Returns:

the HLog

Throws:

java.io.IOException - e

getRootRegion

public HRegion getRootRegion()
                      throws java.io.IOException

Returns:

HRegion for root region

Throws:

java.io.IOException - e

getMetaRegion

public HRegion getMetaRegion(HRegionInfo metaInfo)
                      throws java.io.IOException

Open or return cached opened meta region

Parameters:

metaInfo - HRegionInfo for meta region

Returns:

meta HRegion

Throws:

java.io.IOException - e

shutdown

public void shutdown()

Closes catalog regions if open. Also closes and deletes the HLog. You must call this method if you want to persist changes made during a MetaUtils edit session.

scanRootRegion

public void scanRootRegion(MetaUtils.ScannerListener listener)
                    throws java.io.IOException

Scans the root region. For every meta region found, calls the listener with the HRegionInfo of the meta region.

Parameters:

listener - method to be called for each meta region found

Throws:

java.io.IOException - e

scanMetaRegion

public void scanMetaRegion(HRegion r,
                           MetaUtils.ScannerListener listener)
                    throws java.io.IOException

Scan the passed in metaregion m invoking the passed listener per row found.

Parameters:

r - region

listener - scanner listener

Throws:

java.io.IOException - e

scanMetaRegion

public void scanMetaRegion(HRegionInfo metaRegionInfo,
                           MetaUtils.ScannerListener listener)
                    throws java.io.IOException

Scans a meta region. For every region found, calls the listener with the HRegionInfo of the region. TODO: Use Visitor rather than Listener pattern. Allow multiple Visitors. Use this everywhere we scan meta regions: e.g. in metascanners, in close handling, etc. Have it pass in the whole row, not just HRegionInfo.

Use for reading meta only. Does not close region when done. Use getMetaRegion(HRegionInfo) instead if writing. Adds meta region to list that will get a close on shutdown().

Parameters:

metaRegionInfo - HRegionInfo for meta region

listener - method to be called for each meta region found

Throws:

java.io.IOException - e

changeOnlineStatus

public static void changeOnlineStatus(org.apache.hadoop.conf.Configuration c,
                                      byte[] row,
                                      boolean onlineOffline)
                               throws java.io.IOException

Set a single region on/offline. This is a tool to repair tables that have offlined tables in their midst. Can happen on occasion. Use at your own risk. Call from a bit of java or jython script. This method is 'expensive' in that it creates a HTable instance per invocation to go against .META.

Parameters:

c - A configuration that has its hbase.master properly set.

row - Row in the catalog .META. table whose HRegionInfo's offline status we want to change.

onlineOffline - Pass true to OFFLINE the region.

Throws:

java.io.IOException - e

addColumn

public void addColumn(byte[] tableName,
                      HColumnDescriptor hcd)
               throws java.io.IOException

Offline version of the online TableOperation, org.apache.hadoop.hbase.master.AddColumn.

Parameters:

tableName - table name

hcd - Add this column to tableName

Throws:

java.io.IOException - e

deleteColumn

public void deleteColumn(byte[] tableName,
                         byte[] columnFamily)
                  throws java.io.IOException

Offline version of the online TableOperation, org.apache.hadoop.hbase.master.DeleteColumn.

Parameters:

tableName - table name

columnFamily - Name of column name to remove.

Throws:

java.io.IOException - e

updateMETARegionInfo

public void updateMETARegionInfo(HRegion r,
                                 HRegionInfo hri)
                          throws java.io.IOException

Update COL_REGIONINFO in meta region r with HRegionInfo hri

Parameters:

r - region

hri - region info

Throws:

java.io.IOException - e

getMETARows

public java.util.List<HRegionInfo> getMETARows(byte[] tableName)
                                        throws java.io.IOException

Parameters:

tableName - Name of table to go looking for.

Returns:

List of HRegionInfo rows found in the ROOT or META catalog table.

Throws:

java.io.IOException - e

See Also:

getMetaRegion(HRegionInfo)