org.apache.accumulo.core.client

Class IsolatedScanner

java.lang.Object

org.apache.accumulo.core.client.impl.ScannerOptions

org.apache.accumulo.core.client.IsolatedScanner

All Implemented Interfaces:

Iterable<Map.Entry<Key,Value>>, Scanner, ScannerBase

public class IsolatedScanner
extends org.apache.accumulo.core.client.impl.ScannerOptions
implements Scanner

A scanner that presents a row isolated view of an accumulo table. Rows are buffered in memory on the client side. If you think your rows may not fit into memory, then you can provide an alternative row buffer factory to the constructor. This would allow rows to be buffered to disk for example.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	IsolatedScanner.MemoryRowBuffer
static class	IsolatedScanner.MemoryRowBufferFactory
static interface	IsolatedScanner.RowBuffer
static interface	IsolatedScanner.RowBufferFactory

Field Summary

Fields inherited from class org.apache.accumulo.core.client.impl.ScannerOptions

fetchedColumns, serverSideIteratorList, serverSideIteratorOptions, timeOut

Constructor Summary

Constructors

Constructor and Description
IsolatedScanner(Scanner scanner)
IsolatedScanner(Scanner scanner, IsolatedScanner.RowBufferFactory bufferFactory)

Method Summary

Modifier and Type	Method and Description
void	disableIsolation() Disables row isolation.
void	enableIsolation() Enables row isolation.
int	getBatchSize() Returns the batch size (number of Key/Value pairs) that will be fetched at a time from a tablet server.
Range	getRange() Returns the range of keys to scan over.
long	getReadaheadThreshold() The number of batches of Key/Value pairs returned before the Scanner will begin to prefetch the next batch
int	getTimeOut() Deprecated.
Iterator<Map.Entry<Key,Value>>	iterator() Returns an iterator over an accumulo table.
void	setBatchSize(int size) Sets the number of Key/Value pairs that will be fetched at a time from a tablet server.
void	setRange(Range range) Sets the range of keys to scan over.
void	setReadaheadThreshold(long batches) Sets the number of batches of Key/Value pairs returned before the Scanner will begin to prefetch the next batch
void	setTimeOut(int timeOut) Deprecated.

Methods inherited from class org.apache.accumulo.core.client.impl.ScannerOptions

addScanIterator, clearColumns, clearScanIterators, close, fetchColumn, fetchColumn, fetchColumnFamily, getAuthorizations, getFetchedColumns, getTimeout, removeScanIterator, setOptions, setTimeout, updateScanIteratorOption

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.accumulo.core.client.ScannerBase

addScanIterator, clearColumns, clearScanIterators, close, fetchColumn, fetchColumn, fetchColumnFamily, getAuthorizations, getTimeout, removeScanIterator, setTimeout, updateScanIteratorOption

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Constructor Detail

IsolatedScanner

public IsolatedScanner(Scanner scanner)

IsolatedScanner

public IsolatedScanner(Scanner scanner,
                       IsolatedScanner.RowBufferFactory bufferFactory)

Method Detail

iterator

public Iterator<Map.Entry<Key,Value>> iterator()

Description copied from interface: ScannerBase

Returns an iterator over an accumulo table. This iterator uses the options that are currently set for its lifetime, so setting options will have no effect on existing iterators.

Keys returned by the iterator are not guaranteed to be in sorted order.

Specified by:

iterator in interface Iterable<Map.Entry<Key,Value>>

Specified by:

iterator in interface ScannerBase

Overrides:

iterator in class org.apache.accumulo.core.client.impl.ScannerOptions

Returns:

an iterator over Key,Value pairs which meet the restrictions set on the scanner

setTimeOut

@Deprecated
public void setTimeOut(int timeOut)

Deprecated.

Description copied from interface: Scanner

This setting determines how long a scanner will automatically retry when a failure occurs. By default a scanner will retry forever.

Specified by:

setTimeOut in interface Scanner

Parameters:

timeOut - in seconds

getTimeOut

@Deprecated
public int getTimeOut()

Deprecated.

Description copied from interface: Scanner

Returns the setting for how long a scanner will automatically retry when a failure occurs.

Specified by:

getTimeOut in interface Scanner

Returns:

the timeout configured for this scanner

setRange

public void setRange(Range range)

Description copied from interface: Scanner

Sets the range of keys to scan over.

Specified by:

setRange in interface Scanner

Parameters:

range - key range to begin and end scan

getRange

public Range getRange()

Description copied from interface: Scanner

Returns the range of keys to scan over.

Specified by:

getRange in interface Scanner

Returns:

the range configured for this scanner

setBatchSize

public void setBatchSize(int size)

Description copied from interface: Scanner

Sets the number of Key/Value pairs that will be fetched at a time from a tablet server.

Specified by:

setBatchSize in interface Scanner

Parameters:

size - the number of Key/Value pairs to fetch per call to Accumulo

getBatchSize

public int getBatchSize()

Description copied from interface: Scanner

Returns the batch size (number of Key/Value pairs) that will be fetched at a time from a tablet server.

Specified by:

getBatchSize in interface Scanner

Returns:

the batch size configured for this scanner

enableIsolation

public void enableIsolation()

Description copied from interface: Scanner

Enables row isolation. Writes that occur to a row after a scan of that row has begun will not be seen if this option is enabled.

Specified by:

enableIsolation in interface Scanner

disableIsolation

public void disableIsolation()

Description copied from interface: Scanner

Disables row isolation. Writes that occur to a row after a scan of that row has begun may be seen if this option is enabled.

Specified by:

disableIsolation in interface Scanner

getReadaheadThreshold

public long getReadaheadThreshold()

Description copied from interface: Scanner

The number of batches of Key/Value pairs returned before the Scanner will begin to prefetch the next batch

Specified by:

getReadaheadThreshold in interface Scanner

Returns:

Number of batches before read-ahead begins

setReadaheadThreshold

public void setReadaheadThreshold(long batches)

Description copied from interface: Scanner

Sets the number of batches of Key/Value pairs returned before the Scanner will begin to prefetch the next batch

Specified by:

setReadaheadThreshold in interface Scanner

Parameters:

batches - Non-negative number of batches