org.apache.hadoop.hbase.client

Class ClientSmallReversedScanner

java.lang.Object

org.apache.hadoop.hbase.client.AbstractClientScanner

org.apache.hadoop.hbase.client.ClientScanner

org.apache.hadoop.hbase.client.ReversedClientScanner

org.apache.hadoop.hbase.client.ClientSmallReversedScanner

All Implemented Interfaces:

Closeable, AutoCloseable, Iterable<Result>, ResultScanner

@InterfaceAudience.Public
@InterfaceStability.Evolving
public class ClientSmallReversedScanner
extends ReversedClientScanner

Client scanner for small reversed scan. Generally, only one RPC is called to fetch the scan results, unless the results cross multiple regions or the row count of results exceed the caching.

For small scan, it will get better performance than ReversedClientScanner

Field Summary

Fields inherited from class org.apache.hadoop.hbase.client.ClientScanner

cache, caching, callable, caller, closed, currentRegion, lastNext, lastResult, maxScannerResultSize, rpcControllerFactory, scan, scanMetricsPublished, scannerTimeout

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

scanMetrics

Constructor Summary

Constructors

Constructor and Description
ClientSmallReversedScanner(org.apache.hadoop.conf.Configuration conf, Scan scan, TableName tableName, HConnection connection) Create a new ReversibleClientScanner for the specified table Note that the passed Scan's start row maybe changed.

Method Summary

Methods

Modifier and Type	Method and Description
void	close() Closes the scanner and releases any resources it has allocated
protected void	initializeScannerInConstruction()
protected void	loadCache() Contact the servers to load more Results in the cache.
Result	next() Grab the next row's worth of values.
protected void	setRpcControllerFactory(RpcControllerFactory rpcControllerFactory)
protected void	setRpcRetryingCaller(RpcRetryingCaller<Result[]> caller)
protected void	setScannerCallableFactory(ClientSmallScanner.SmallScannerCallableFactory callableFactory)

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

checkScanStopRow, createClosestRowBefore, getScannerCallable, nextScanner

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

getConnection, getScan, getScannerCallable, getTable, getTableName, getTimestamp, writeScanMetrics

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

getScanMetrics, initScanMetrics, iterator, next

Methods inherited from class java.lang.Object

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

Constructor Detail

ClientSmallReversedScanner

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

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

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.

Specified by:

next in interface ResultScanner

Overrides:

next in class ClientScanner

Returns:

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

Throws:

IOException - e

loadCache

protected void loadCache()
                  throws IOException

Description copied from class: ClientScanner

Contact the servers to load more Results in the cache.

Overrides:

loadCache in class ClientScanner

Throws:

IOException

initializeScannerInConstruction

protected void initializeScannerInConstruction()
                                        throws IOException

Overrides:

initializeScannerInConstruction in class ClientScanner

Throws:

IOException

close

public void close()

Description copied from interface: ResultScanner

Closes the scanner and releases any resources it has allocated

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Specified by:

close in interface ResultScanner

Overrides:

close in class ClientScanner

setScannerCallableFactory

protected void setScannerCallableFactory(ClientSmallScanner.SmallScannerCallableFactory callableFactory)

setRpcRetryingCaller

protected void setRpcRetryingCaller(RpcRetryingCaller<Result[]> caller)

setRpcControllerFactory

protected void setRpcControllerFactory(RpcControllerFactory rpcControllerFactory)