Package org.apache.hadoop.hbase.regionserver

Class ReversedStoreScanner

java.lang.Object

org.apache.hadoop.hbase.regionserver.NonLazyKeyValueScanner

org.apache.hadoop.hbase.regionserver.NonReversedNonLazyKeyValueScanner

org.apache.hadoop.hbase.regionserver.StoreScanner

org.apache.hadoop.hbase.regionserver.ReversedStoreScanner

All Implemented Interfaces:

Closeable, AutoCloseable, ChangedReadersObserver, InternalScanner, KeyValueScanner, Shipper

Direct Known Subclasses:

ReversedMobStoreScanner

@Private
public class ReversedStoreScanner
extends StoreScanner
implements KeyValueScanner

ReversedStoreScanner extends from StoreScanner, and is used to support reversed scanning.

Field Summary

Fields inherited from class org.apache.hadoop.hbase.regionserver.StoreScanner

currentScanners, DEFAULT_HBASE_CELLS_SCANNED_PER_HEARTBEAT_CHECK, HBASE_CELLS_SCANNED_PER_HEARTBEAT_CHECK, heap, LAZY_SEEK_ENABLED_BY_DEFAULT, memstoreOnlyReads, mixedReads, readPt, store, STORESCANNER_PARALLEL_SEEK_ENABLE, STORESCANNER_PREAD_MAX_BYTES

Fields inherited from interface org.apache.hadoop.hbase.regionserver.KeyValueScanner

NO_NEXT_INDEXED_KEY

Constructor Summary

Constructors

Constructor	Description
ReversedStoreScanner(Scan scan, ScanInfo scanInfo, NavigableSet<byte[]> columns, List<? extends KeyValueScanner> scanners)	Constructor for testing.
ReversedStoreScanner(HStore store, ScanInfo scanInfo, Scan scan, NavigableSet<byte[]> columns, long readPt)	Opens a scanner across memstore, snapshot, and all StoreFiles.

Method Summary

Modifier and Type	Method	Description
boolean	backwardSeek(Cell key)	Seek the scanner at or before the row of specified Cell, it firstly tries to seek the scanner at or after the specified Cell, return if peek KeyValue of scanner has the same row with specified Cell, otherwise seek the scanner at the first Cell of the row which is the previous row of specified KeyValue
protected void	checkScanOrder(Cell prevKV, Cell kv, CellComparator comparator)	Check whether scan as expected order
protected KeyValueHeap	newKVHeap(List<? extends KeyValueScanner> scanners, CellComparator comparator)
boolean	reseek(Cell kv)	Reseek the scanner at or after the specified KeyValue.
boolean	seek(Cell key)	Seek the scanner at or after the specified KeyValue.
protected boolean	seekAsDirection(Cell kv)	Do a backwardSeek in a reversed StoreScanner(scan backward)
protected void	seekScanners(List<? extends KeyValueScanner> scanners, Cell seekKey, boolean isLazy, boolean isParallelSeek)	Seek the specified scanners with the given key
protected boolean	seekToNextRow(Cell kv)
boolean	seekToPreviousRow(Cell key)	Seek the scanner at the first Cell of the row which is the previous row of specified key

Methods inherited from class org.apache.hadoop.hbase.regionserver.StoreScanner

checkFlushed, close, enableLazySeekGlobally, getAllScannersForTesting, getEstimatedNumberOfKvsScanned, getNextIndexedKey, getReadPoint, isScanUsePread, next, next, peek, reopenAfterFlush, resetKVHeap, selectScannersFrom, shipped, trySkipToNextColumn, trySkipToNextRow, trySwitchToStreamRead, updateReaders

Methods inherited from class org.apache.hadoop.hbase.regionserver.NonReversedNonLazyKeyValueScanner

seekToLastRow

Methods inherited from class org.apache.hadoop.hbase.regionserver.NonLazyKeyValueScanner

doRealSeek, enforceSeek, getFilePath, isFileScanner, realSeekDone, recordBlockSize, requestSeek, shouldUseScanner

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.hadoop.hbase.regionserver.InternalScanner

next

Methods inherited from interface org.apache.hadoop.hbase.regionserver.KeyValueScanner

close, enforceSeek, getFilePath, getNextIndexedKey, getScannerOrder, isFileScanner, next, peek, realSeekDone, recordBlockSize, requestSeek, seekToLastRow, shouldUseScanner

Methods inherited from interface org.apache.hadoop.hbase.regionserver.Shipper

shipped

Constructor Details

ReversedStoreScanner

public ReversedStoreScanner(HStore store,
 ScanInfo scanInfo,
 Scan scan,
 NavigableSet<byte[]> columns,
 long readPt)
                     throws IOException

Opens a scanner across memstore, snapshot, and all StoreFiles. Assumes we are not in a compaction.

Parameters:

store - who we scan

scan - the spec

columns - which columns we are scanning

Throws:

IOException

ReversedStoreScanner

public ReversedStoreScanner(Scan scan,
 ScanInfo scanInfo,
 NavigableSet<byte[]> columns,
 List<? extends KeyValueScanner> scanners)
                     throws IOException

Constructor for testing.

Throws:

IOException

Method Details

newKVHeap

protected KeyValueHeap newKVHeap(List<? extends KeyValueScanner> scanners,
 CellComparator comparator)
                          throws IOException

Overrides:

newKVHeap in class StoreScanner

Throws:

IOException

seekScanners

protected void seekScanners(List<? extends KeyValueScanner> scanners,
 Cell seekKey,
 boolean isLazy,
 boolean isParallelSeek)
                     throws IOException

Description copied from class: StoreScanner

Seek the specified scanners with the given key

Overrides:

seekScanners in class StoreScanner

isLazy - true if using lazy seek

isParallelSeek - true if using parallel seek

Throws:

IOException

seekToNextRow

protected boolean seekToNextRow(Cell kv)
                         throws IOException

Overrides:

seekToNextRow in class StoreScanner

Throws:

IOException

seekAsDirection

protected boolean seekAsDirection(Cell kv)
                           throws IOException

Do a backwardSeek in a reversed StoreScanner(scan backward)

Overrides:

seekAsDirection in class StoreScanner

Returns:

true if scanner has values left, false if end of scanner

Throws:

IOException

checkScanOrder

protected void checkScanOrder(Cell prevKV,
 Cell kv,
 CellComparator comparator)
                       throws IOException

Description copied from class: StoreScanner

Check whether scan as expected order

Overrides:

checkScanOrder in class StoreScanner

Throws:

IOException

reseek

public boolean reseek(Cell kv)
               throws IOException

Description copied from interface: KeyValueScanner

Reseek the scanner at or after the specified KeyValue. This method is guaranteed to seek at or after the required key only if the key comes after the current position of the scanner. Should not be used to seek to a key which may come before the current position.

Specified by:

reseek in interface KeyValueScanner

Overrides:

reseek in class StoreScanner

Parameters:

kv - seek value (should be non-null)

Returns:

true if scanner has values left, false if end of scanner

Throws:

IOException

seek

public boolean seek(Cell key)
             throws IOException

Description copied from interface: KeyValueScanner

Seek the scanner at or after the specified KeyValue.

Specified by:

seek in interface KeyValueScanner

Overrides:

seek in class StoreScanner

Parameters:

key - seek value

Returns:

true if scanner has values left, false if end of scanner

Throws:

IOException

seekToPreviousRow

public boolean seekToPreviousRow(Cell key)
                          throws IOException

Description copied from interface: KeyValueScanner

Seek the scanner at the first Cell of the row which is the previous row of specified key

Specified by:

seekToPreviousRow in interface KeyValueScanner

Overrides:

seekToPreviousRow in class NonReversedNonLazyKeyValueScanner

Parameters:

key - seek value

Returns:

true if the scanner at the first valid Cell of previous row, false if not existing such Cell

Throws:

IOException

backwardSeek

public boolean backwardSeek(Cell key)
                     throws IOException

Description copied from interface: KeyValueScanner

Seek the scanner at or before the row of specified Cell, it firstly tries to seek the scanner at or after the specified Cell, return if peek KeyValue of scanner has the same row with specified Cell, otherwise seek the scanner at the first Cell of the row which is the previous row of specified KeyValue

Specified by:

backwardSeek in interface KeyValueScanner

Overrides:

backwardSeek in class NonReversedNonLazyKeyValueScanner

Parameters:

key - seek KeyValue

Returns:

true if the scanner is at the valid KeyValue, false if such KeyValue does not exist

Throws:

IOException