org.apache.hadoop.hbase.client

Class MetaScanner

java.lang.Object

org.apache.hadoop.hbase.client.MetaScanner

@InterfaceAudience.Private
public class MetaScanner
extends Object

Scanner class that contains the hbase:meta table scanning logic. Provided visitors will be called for each row. Although public visibility, this is not a public-facing API and may evolve in minor releases.

Note that during concurrent region splits, the scanner might not see hbase:meta changes across rows (for parent and daughter entries) consistently. see HBASE-5986, and MetaScanner.DefaultMetaScannerVisitor for details.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	MetaScanner.DefaultMetaScannerVisitor A MetaScannerVisitor that skips offline regions and split parents
static interface	MetaScanner.MetaScannerVisitor Visitor class called to process each row of the hbase:meta table
static class	MetaScanner.MetaScannerVisitorBase
static class	MetaScanner.TableMetaScannerVisitor A MetaScannerVisitor for a table.

Constructor Summary

Constructors

Constructor and Description
MetaScanner()

Method Summary

Methods

Modifier and Type	Method and Description
static NavigableMap<HRegionInfo,ServerName>	allTableRegions(org.apache.hadoop.conf.Configuration conf, HConnection connection, TableName tableName, boolean offlined) Lists all of the table regions currently in META.
static HRegionInfo	getHRegionInfo(Result data) Returns HRegionInfo object from the column HConstants.CATALOG_FAMILY:HConstants.REGIONINFO_QUALIFIER of the catalog table Result.
static List<HRegionInfo>	listAllRegions(org.apache.hadoop.conf.Configuration conf, boolean offlined) Used in tests.
static void	metaScan(org.apache.hadoop.conf.Configuration configuration, HConnection connection, MetaScanner.MetaScannerVisitor visitor, TableName userTableName) Scans the meta table and calls a visitor on each RowResult.
static void	metaScan(org.apache.hadoop.conf.Configuration configuration, HConnection connection, MetaScanner.MetaScannerVisitor visitor, TableName tableName, byte[] row, int rowLimit, TableName metaTableName) Scans the meta table and calls a visitor on each RowResult.
static void	metaScan(org.apache.hadoop.conf.Configuration configuration, MetaScanner.MetaScannerVisitor visitor) Scans the meta table and calls a visitor on each RowResult and uses a empty start row value as table name.
static void	metaScan(org.apache.hadoop.conf.Configuration configuration, MetaScanner.MetaScannerVisitor visitor, TableName userTableName, byte[] row, int rowLimit) Scans the meta table and calls a visitor on each RowResult.

Methods inherited from class java.lang.Object

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

Constructor Detail

MetaScanner

public MetaScanner()

Method Detail

metaScan

public static void metaScan(org.apache.hadoop.conf.Configuration configuration,
            MetaScanner.MetaScannerVisitor visitor)
                     throws IOException

Scans the meta table and calls a visitor on each RowResult and uses a empty start row value as table name.

Parameters:

configuration - conf

visitor - A custom visitor

Throws:

IOException - e

metaScan

public static void metaScan(org.apache.hadoop.conf.Configuration configuration,
            HConnection connection,
            MetaScanner.MetaScannerVisitor visitor,
            TableName userTableName)
                     throws IOException

Scans the meta table and calls a visitor on each RowResult. Uses a table name to locate meta regions.

Parameters:

configuration - config

connection - connection to use internally (null to use a new instance)

visitor - visitor object

userTableName - User table name in meta table to start scan at. Pass null if not interested in a particular table.

Throws:

IOException - e

metaScan

public static void metaScan(org.apache.hadoop.conf.Configuration configuration,
            MetaScanner.MetaScannerVisitor visitor,
            TableName userTableName,
            byte[] row,
            int rowLimit)
                     throws IOException

Scans the meta table and calls a visitor on each RowResult. Uses a table name and a row name to locate meta regions. And it only scans at most rowLimit of rows.

Parameters:

configuration - HBase configuration.

visitor - Visitor object.

userTableName - User table name in meta table to start scan at. Pass null if not interested in a particular table.

row - Name of the row at the user table. The scan will start from the region row where the row resides.

rowLimit - Max of processed rows. If it is less than 0, it will be set to default value Integer.MAX_VALUE.

Throws:

IOException - e

metaScan

public static void metaScan(org.apache.hadoop.conf.Configuration configuration,
            HConnection connection,
            MetaScanner.MetaScannerVisitor visitor,
            TableName tableName,
            byte[] row,
            int rowLimit,
            TableName metaTableName)
                     throws IOException

Scans the meta table and calls a visitor on each RowResult. Uses a table name and a row name to locate meta regions. And it only scans at most rowLimit of rows.

Parameters:

configuration - HBase configuration.

connection - connection to use internally (null to use a new instance)

visitor - Visitor object. Closes the visitor before returning.

tableName - User table name in meta table to start scan at. Pass null if not interested in a particular table.

row - Name of the row at the user table. The scan will start from the region row where the row resides.

rowLimit - Max of processed rows. If it is less than 0, it will be set to default value Integer.MAX_VALUE.

metaTableName - Meta table to scan, root or meta.

Throws:

IOException - e

getHRegionInfo

public static HRegionInfo getHRegionInfo(Result data)

Returns HRegionInfo object from the column HConstants.CATALOG_FAMILY:HConstants.REGIONINFO_QUALIFIER of the catalog table Result.

Parameters:

data - a Result object from the catalog table scan

Returns:

HRegionInfo or null

listAllRegions

public static List<HRegionInfo> listAllRegions(org.apache.hadoop.conf.Configuration conf,
                               boolean offlined)
                                        throws IOException

Used in tests. Lists all of the regions currently in META.

Parameters:

conf -

offlined - True if we are to include offlined regions, false and we'll leave out offlined regions from returned list.

Returns:

List of all user-space regions.

Throws:

IOException

allTableRegions

public static NavigableMap<HRegionInfo,ServerName> allTableRegions(org.apache.hadoop.conf.Configuration conf,
                                                   HConnection connection,
                                                   TableName tableName,
                                                   boolean offlined)
                                                            throws IOException

Lists all of the table regions currently in META.

Parameters:

conf -

offlined - True if we are to include offlined regions, false and we'll leave out offlined regions from returned list.

Returns:

Map of all user-space regions to servers

Throws:

IOException