org.apache.hadoop.hbase.snapshot

Class RestoreSnapshotHelper

java.lang.Object

org.apache.hadoop.hbase.snapshot.RestoreSnapshotHelper

@InterfaceAudience.Private
public class RestoreSnapshotHelper
extends Object

Helper to Restore/Clone a Snapshot

The helper assumes that a table is already created, and by calling restore() the content present in the snapshot will be restored as the new content of the table.

Clone from Snapshot: If the target table is empty, the restore operation is just a "clone operation", where the only operations are:

• for each region in the snapshot create a new region (note that the region will have a different name, since the encoding contains the table name)
• for each file in the region create a new HFileLink to point to the original file.
• restore the logs, if any

Restore from Snapshot:

• for each region in the table verify which are available in the snapshot and which are not
  • if the region is not present in the snapshot, remove it.
  • if the region is present in the snapshot
    • for each file in the table region verify which are available in the snapshot
      • if the hfile is not present in the snapshot, remove it
      • if the hfile is present, keep it (nothing to do)
    • for each file in the snapshot region but not in the table
      • create a new HFileLink that point to the original file
• for each region in the snapshot not present in the current table state
  • create a new region and for each file in the region create a new HFileLink (This is the same as the clone operation)
• restore the logs, if any

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	RestoreSnapshotHelper.RestoreMetaChanges Describe the set of operations needed to update hbase:meta after restore.

Constructor Summary

Constructors

Constructor and Description
RestoreSnapshotHelper(org.apache.hadoop.conf.Configuration conf, org.apache.hadoop.fs.FileSystem fs, SnapshotManifest manifest, HTableDescriptor tableDescriptor, org.apache.hadoop.fs.Path rootDir, ForeignExceptionDispatcher monitor, MonitoredTask status)
RestoreSnapshotHelper(org.apache.hadoop.conf.Configuration conf, org.apache.hadoop.fs.FileSystem fs, SnapshotManifest manifest, HTableDescriptor tableDescriptor, org.apache.hadoop.fs.Path rootDir, ForeignExceptionDispatcher monitor, MonitoredTask status, boolean createBackRefs)

Method Summary

Methods

Modifier and Type	Method and Description
HRegionInfo	cloneRegionInfo(HRegionInfo snapshotRegionInfo) Create a new HRegionInfo from the snapshot region info.
static HTableDescriptor	cloneTableSchema(HTableDescriptor snapshotTableDescriptor, TableName tableName) Create a new table descriptor cloning the snapshot table schema.
static void	copySnapshotForScanner(org.apache.hadoop.conf.Configuration conf, org.apache.hadoop.fs.FileSystem fs, org.apache.hadoop.fs.Path rootDir, org.apache.hadoop.fs.Path restoreDir, String snapshotName) Copy the snapshot files for a snapshot scanner, discards meta changes.
RestoreSnapshotHelper.RestoreMetaChanges	restoreHdfsRegions() Restore the on-disk table to a specified snapshot state.

Methods inherited from class java.lang.Object

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

Constructor Detail

RestoreSnapshotHelper

public RestoreSnapshotHelper(org.apache.hadoop.conf.Configuration conf,
                     org.apache.hadoop.fs.FileSystem fs,
                     SnapshotManifest manifest,
                     HTableDescriptor tableDescriptor,
                     org.apache.hadoop.fs.Path rootDir,
                     ForeignExceptionDispatcher monitor,
                     MonitoredTask status)

RestoreSnapshotHelper

public RestoreSnapshotHelper(org.apache.hadoop.conf.Configuration conf,
                     org.apache.hadoop.fs.FileSystem fs,
                     SnapshotManifest manifest,
                     HTableDescriptor tableDescriptor,
                     org.apache.hadoop.fs.Path rootDir,
                     ForeignExceptionDispatcher monitor,
                     MonitoredTask status,
                     boolean createBackRefs)

Method Detail

restoreHdfsRegions

public RestoreSnapshotHelper.RestoreMetaChanges restoreHdfsRegions()
                                                            throws IOException

Restore the on-disk table to a specified snapshot state.

Returns:

the set of regions touched by the restore operation

Throws:

IOException

cloneRegionInfo

public HRegionInfo cloneRegionInfo(HRegionInfo snapshotRegionInfo)

Create a new HRegionInfo from the snapshot region info. Keep the same startKey, endKey, regionId and split information but change the table name.

Parameters:

snapshotRegionInfo - Info for region to clone.

Returns:

the new HRegion instance

cloneTableSchema

public static HTableDescriptor cloneTableSchema(HTableDescriptor snapshotTableDescriptor,
                                TableName tableName)
                                         throws IOException

Create a new table descriptor cloning the snapshot table schema.

Parameters:

snapshotTableDescriptor -

tableName -

Returns:

cloned table descriptor

Throws:

IOException

copySnapshotForScanner

public static void copySnapshotForScanner(org.apache.hadoop.conf.Configuration conf,
                          org.apache.hadoop.fs.FileSystem fs,
                          org.apache.hadoop.fs.Path rootDir,
                          org.apache.hadoop.fs.Path restoreDir,
                          String snapshotName)
                                   throws IOException

Copy the snapshot files for a snapshot scanner, discards meta changes.

Parameters:

conf -

fs -

rootDir -

restoreDir -

snapshotName -

Throws:

IOException