org.apache.hadoop.hbase.client

Class ClientScanner

java.lang.Object

org.apache.hadoop.hbase.client.AbstractClientScanner

org.apache.hadoop.hbase.client.ClientScanner

All Implemented Interfaces:

Closeable, AutoCloseable, Iterable<Result>, ResultScanner

Direct Known Subclasses:

ClientSmallScanner

@InterfaceAudience.Public
@InterfaceStability.Stable
public class ClientScanner
extends AbstractClientScanner

Implements the scanner interface for the HBase client. If there are multiple regions in a table, this scanner will iterate through them all.

Field Summary

Fields

Modifier and Type	Field and Description
protected LinkedList<Result>	cache
protected int	caching
protected RpcRetryingCaller<Result[]>	caller
protected boolean	closed
protected HRegionInfo	currentRegion
protected long	lastNext
protected Result	lastResult
protected long	maxScannerResultSize
protected Scan	scan
protected ScanMetrics	scanMetrics
protected boolean	scanMetricsPublished

Constructor Summary

Constructors

Constructor and Description
ClientScanner(org.apache.hadoop.conf.Configuration conf, Scan scan, byte[] tableName) Deprecated. Use ClientScanner(Configuration, Scan, TableName)
ClientScanner(org.apache.hadoop.conf.Configuration conf, Scan scan, byte[] tableName, HConnection connection) Deprecated. Use ClientScanner(Configuration, Scan, TableName, HConnection)
ClientScanner(org.apache.hadoop.conf.Configuration conf, Scan scan, TableName tableName) Create a new ClientScanner for the specified table.
ClientScanner(org.apache.hadoop.conf.Configuration conf, Scan scan, TableName tableName, HConnection connection) Create a new ClientScanner for the specified table Note that the passed Scan's start row maybe changed changed.
ClientScanner(org.apache.hadoop.conf.Configuration conf, Scan scan, TableName tableName, HConnection connection, RpcRetryingCallerFactory rpcFactory) Create a new ClientScanner for the specified table Note that the passed Scan's start row maybe changed changed.

Method Summary

Methods

Modifier and Type	Method and Description
protected boolean	checkScanStopRow(byte[] endKey)
void	close() Closes the scanner and releases any resources it has allocated
protected HConnection	getConnection()
protected Scan	getScan()
protected ScannerCallable	getScannerCallable(byte[] localStartKey, int nbRows)
protected TableName	getTable()
protected byte[]	getTableName() Deprecated. Since 0.96.0; use getTable()
protected long	getTimestamp()
protected void	initializeScannerInConstruction()
Result	next() Grab the next row's worth of values.
Result[]	next(int nbRows) Get nbRows rows.
protected void	writeScanMetrics() Publish the scan metrics.

Methods inherited from class org.apache.hadoop.hbase.client.AbstractClientScanner

iterator

Methods inherited from class java.lang.Object

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

Field Detail

scan

protected Scan scan

closed

protected boolean closed

currentRegion

protected HRegionInfo currentRegion

cache

protected final LinkedList<Result> cache

caching

protected final int caching

lastNext

protected long lastNext

lastResult

protected Result lastResult

scanMetrics

protected ScanMetrics scanMetrics

maxScannerResultSize

protected final long maxScannerResultSize

scanMetricsPublished

protected boolean scanMetricsPublished

caller

protected RpcRetryingCaller<Result[]> caller

Constructor Detail

ClientScanner

public ClientScanner(org.apache.hadoop.conf.Configuration conf,
             Scan scan,
             TableName tableName)
              throws IOException

Create a new ClientScanner for the specified table. An HConnection will be retrieved using the passed Configuration. Note that the passed Scan's start row maybe changed changed.

Parameters:

conf - The Configuration to use.

scan - Scan to use in this scanner

tableName - The table that we wish to scan

Throws:

IOException

ClientScanner

@Deprecated
public ClientScanner(org.apache.hadoop.conf.Configuration conf,
                        Scan scan,
                        byte[] tableName)
              throws IOException

Deprecated. Use ClientScanner(Configuration, Scan, TableName)

Throws:

IOException

ClientScanner

public ClientScanner(org.apache.hadoop.conf.Configuration conf,
             Scan scan,
             TableName tableName,
             HConnection connection)
              throws IOException

Create a new ClientScanner for the specified table Note that the passed Scan's start row maybe changed changed.

Parameters:

conf - The Configuration to use.

scan - Scan to use in this scanner

tableName - The table that we wish to scan

connection - Connection identifying the cluster

Throws:

IOException

ClientScanner

@Deprecated
public ClientScanner(org.apache.hadoop.conf.Configuration conf,
                        Scan scan,
                        byte[] tableName,
                        HConnection connection)
              throws IOException

Deprecated. Use ClientScanner(Configuration, Scan, TableName, HConnection)

Throws:

IOException

ClientScanner

public ClientScanner(org.apache.hadoop.conf.Configuration conf,
             Scan scan,
             TableName tableName,
             HConnection connection,
             RpcRetryingCallerFactory rpcFactory)
              throws IOException

Create a new ClientScanner for the specified table Note that the passed Scan's start row maybe changed changed.

Parameters:

conf - The Configuration to use.

scan - Scan to use in this scanner

tableName - The table that we wish to scan

connection - Connection identifying the cluster

Throws:

IOException

Method Detail

initializeScannerInConstruction

protected void initializeScannerInConstruction()
                                        throws IOException

Throws:

IOException

getConnection

protected HConnection getConnection()

getTableName

@Deprecated
protected byte[] getTableName()

Deprecated. Since 0.96.0; use getTable()

Returns:

Table name

getTable

protected TableName getTable()

getScan

protected Scan getScan()

getTimestamp

protected long getTimestamp()

checkScanStopRow

protected boolean checkScanStopRow(byte[] endKey)

getScannerCallable

@InterfaceAudience.Private
protected ScannerCallable getScannerCallable(byte[] localStartKey,
                                                           int nbRows)

writeScanMetrics

protected void writeScanMetrics()

Publish the scan metrics. For now, we use scan.setAttribute to pass the metrics back to the application or TableInputFormat.Later, we could push it to other systems. We don't use metrics framework because it doesn't support multi-instances of the same metrics on the same machine; for scan/map reduce scenarios, we will have multiple scans running at the same time. By default, scan metrics are disabled; if the application wants to collect them, this behavior can be turned on by calling calling: scan.setAttribute(SCAN_ATTRIBUTES_METRICS_ENABLE, Bytes.toBytes(Boolean.TRUE))

next

public Result next()
            throws IOException

Description copied from interface: ResultScanner

Grab the next row's worth of values. The scanner will return a Result.

Returns:

Result object if there is another row, null if the scanner is exhausted.

Throws:

IOException - e

next

public Result[] next(int nbRows)
              throws IOException

Get nbRows rows. How many RPCs are made is determined by the Scan.setCaching(int) setting (or hbase.client.scanner.caching in hbase-site.xml).

Parameters:

nbRows - number of rows to return

Returns:

Between zero and nbRows RowResults. Scan is done if returned array is of zero-length (We never return null).

Throws:

IOException

close

public void close()

Description copied from interface: ResultScanner

Closes the scanner and releases any resources it has allocated