Package org.apache.accumulo.core.client
Interface Scanner
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- 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."
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Nested Class Summary
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Nested classes/interfaces inherited from interface org.apache.accumulo.core.client.ScannerBase
ScannerBase.ConsistencyLevel
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Method Summary
All Methods Instance Methods Abstract Methods 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 theScanner
will begin to prefetch the next batchvoid
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 theScanner
will begin to prefetch the next batch-
Methods inherited from interface java.lang.Iterable
forEach, spliterator
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Methods inherited from interface org.apache.accumulo.core.client.ScannerBase
addScanIterator, clearClassLoaderContext, clearColumns, clearSamplerConfiguration, clearScanIterators, close, fetchColumn, fetchColumn, fetchColumn, fetchColumnFamily, fetchColumnFamily, forEach, getAuthorizations, getBatchTimeout, getClassLoaderContext, getConsistencyLevel, getSamplerConfiguration, getTimeout, iterator, removeScanIterator, setBatchTimeout, setClassLoaderContext, setConsistencyLevel, setExecutionHints, setSamplerConfiguration, setTimeout, stream, updateScanIteratorOption
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Method Detail
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setRange
void setRange(Range range)
Sets the range of keys to scan over.- Parameters:
range
- key range to begin and end scan
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getRange
Range getRange()
Returns the range of keys to scan over.- Returns:
- the range configured for this scanner
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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
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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
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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.
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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.
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getReadaheadThreshold
long getReadaheadThreshold()
The number of batches of Key/Value pairs returned before theScanner
will begin to prefetch the next batch- Returns:
- Number of batches before read-ahead begins
- Since:
- 1.6.0
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setReadaheadThreshold
void setReadaheadThreshold(long batches)
Sets the number of batches of Key/Value pairs returned before theScanner
will begin to prefetch the next batch- Parameters:
batches
- Non-negative number of batches- Since:
- 1.6.0
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