Package org.apache.accumulo.core.client

Interface Scanner

All Superinterfaces:

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

All Known Implementing Classes:

ClientSideIteratorScanner, IsolatedScanner, OfflineScanner, ScannerImpl

public interface Scanner
extends ScannerBase

Scans a table over a given range. "Clients can iterate over multiple column families, and there are several mechanisms for limiting the rows, columns, and timestamps traversed by a scan. For example, we could restrict [a] scan ... to only produce anchors whose columns match [a] regular expression ..., or to only produce anchors whose timestamps fall within ten days of the current time."

Method Summary

Modifier and Type	Method	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
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

Methods inherited from interface java.lang.Iterable

forEach, spliterator

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

addScanIterator, clearClassLoaderContext, clearColumns, clearSamplerConfiguration, clearScanIterators, close, fetchColumn, fetchColumn, fetchColumn, fetchColumnFamily, fetchColumnFamily, getAuthorizations, getBatchTimeout, getClassLoaderContext, getSamplerConfiguration, getTimeout, iterator, removeScanIterator, setBatchTimeout, setClassLoaderContext, setExecutionHints, setSamplerConfiguration, setTimeout, updateScanIteratorOption

Method Detail

setRange

void setRange(Range range)

Sets the range of keys to scan over.

Parameters:

range - key range to begin and end scan

getRange

Range getRange()

Returns the range of keys to scan over.

Returns:

the range configured for this scanner

setBatchSize

void setBatchSize(int size)

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

Parameters:

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

getBatchSize

int getBatchSize()

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

Returns:

the batch size configured for this scanner

enableIsolation

void enableIsolation()

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.

disableIsolation

void disableIsolation()

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.

getReadaheadThreshold

long getReadaheadThreshold()

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

Returns:

Number of batches before read-ahead begins

Since:

1.6.0

setReadaheadThreshold

void setReadaheadThreshold(long batches)

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

Parameters:

batches - Non-negative number of batches

Since:

1.6.0