Package org.apache.hadoop.hbase.regionserver.querymatcher

Class ScanWildcardColumnTracker

java.lang.Object

org.apache.hadoop.hbase.regionserver.querymatcher.ScanWildcardColumnTracker

All Implemented Interfaces:

ColumnTracker, ShipperListener

@Private
public class ScanWildcardColumnTracker
extends Object
implements ColumnTracker

Keeps track of the columns for a scan if they are not explicitly specified

Field Summary

Fields

Modifier and Type	Field	Description
private Cell	columnCell
private final CellComparator	comparator
private int	currentCount
private long	latestTSOfCurrentColumn
private byte	latestTypeOfCurrentColumn
private final int	maxVersions
private final int	minVersions
private long	oldestStamp

Constructor Summary

Constructors

Constructor	Description
ScanWildcardColumnTracker(int minVersion, int maxVersion, long oldestUnexpiredTS, CellComparator comparator)	Return maxVersions of every row.

Method Summary

Modifier and Type	Method	Description
void	beforeShipped()	The action that needs to be performed before Shipper.shipped() is performed
ScanQueryMatcher.MatchCode	checkColumn(Cell cell, byte type)	Checks if the column is present in the list of requested columns by returning the match code instance.
private ScanQueryMatcher.MatchCode	checkVersion(byte type, long timestamp)	Check whether this version should be retained.
ScanQueryMatcher.MatchCode	checkVersions(Cell cell, long timestamp, byte type, boolean ignoreCount)	Keeps track of the number of versions for the columns asked for.
boolean	done()	We can never know a-priori if we are done, so always return false.
ColumnCount	getColumnHint()	Used by matcher and scan/get to get a hint of the next column to seek to after checkColumn() returns SKIP.
ScanQueryMatcher.MatchCode	getNextRowOrNextColumn(Cell cell)	Retrieve the MatchCode for the next row or column
boolean	isDone(long timestamp)	Give the tracker a chance to declare it's done based on only the timestamp to allow an early out.
private boolean	isExpired(long timestamp)
void	reset()	Resets the Matcher
private void	resetCell(Cell columnCell)
private void	resetTSAndType()
private boolean	sameAsPreviousTSAndType(long timestamp, byte type)
private void	setTSAndType(long timestamp, byte type)

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.querymatcher.ColumnTracker

doneWithColumn

Field Details

columnCell

private Cell columnCell

currentCount

private int currentCount

maxVersions

private final int maxVersions

minVersions

private final int minVersions

latestTSOfCurrentColumn

private long latestTSOfCurrentColumn

latestTypeOfCurrentColumn

private byte latestTypeOfCurrentColumn

oldestStamp

private long oldestStamp

comparator

private final CellComparator comparator

Constructor Details

ScanWildcardColumnTracker

public ScanWildcardColumnTracker(int minVersion,
 int maxVersion,
 long oldestUnexpiredTS,
 CellComparator comparator)

Return maxVersions of every row.

Parameters:

minVersion - Minimum number of versions to keep

maxVersion - Maximum number of versions to return

oldestUnexpiredTS - oldest timestamp that has not expired according to the TTL.

comparator - used to compare the qualifier of cell

Method Details

checkColumn

public ScanQueryMatcher.MatchCode checkColumn(Cell cell,
 byte type)
                                       throws IOException

Checks if the column is present in the list of requested columns by returning the match code instance. It does not check against the number of versions for the columns asked for. To do the version check, one has to call ColumnTracker.checkVersions(Cell, long, byte, boolean) method based on the return type (INCLUDE) of this method. The values that can be returned by this method are ScanQueryMatcher.MatchCode.INCLUDE, ScanQueryMatcher.MatchCode.SEEK_NEXT_COL and ScanQueryMatcher.MatchCode.SEEK_NEXT_ROW. This receives puts *and* deletes.

Specified by:

checkColumn in interface ColumnTracker

Parameters:

cell - a cell with the column to match against

type - The type of the Cell

Returns:

The match code instance.

Throws:

IOException - in case there is an internal consistency problem caused by a data corruption.

checkVersions

public ScanQueryMatcher.MatchCode checkVersions(Cell cell,
 long timestamp,
 byte type,
 boolean ignoreCount)
                                         throws IOException

Keeps track of the number of versions for the columns asked for. It assumes that the user has already checked if the cell needs to be included by calling the ColumnTracker.checkColumn(Cell, byte) method. The enum values returned by this method are ScanQueryMatcher.MatchCode.SKIP, ScanQueryMatcher.MatchCode.INCLUDE, ScanQueryMatcher.MatchCode.INCLUDE_AND_SEEK_NEXT_COL and ScanQueryMatcher.MatchCode.INCLUDE_AND_SEEK_NEXT_ROW. Implementations which include all the columns could just return ScanQueryMatcher.MatchCode.INCLUDE in the ColumnTracker.checkColumn(Cell, byte) method and perform all the operations in this checkVersions method. This receives puts *and* deletes. Deletes do not count as a version, but rather take the version of the previous put (so eventually all but the last can be reclaimed).

Specified by:

checkVersions in interface ColumnTracker

Parameters:

cell - a cell with the column to match against

timestamp - The timestamp of the cell.

type - the type of the key value (Put/Delete)

ignoreCount - indicates if the KV needs to be excluded while counting (used during compactions. We only count KV's that are older than all the scanners' read points.)

Returns:

the scan query matcher match code instance

Throws:

IOException - in case there is an internal consistency problem caused by a data corruption.

resetCell

private void resetCell(Cell columnCell)

checkVersion

private ScanQueryMatcher.MatchCode checkVersion(byte type,
 long timestamp)

Check whether this version should be retained. There are 4 variables considered: If this version is past max versions -> skip it If this kv has expired or was deleted, check min versions to decide whther to skip it or not. Increase the version counter unless this is a delete

reset

public void reset()

Description copied from interface: ColumnTracker

Resets the Matcher

Specified by:

reset in interface ColumnTracker

resetTSAndType

private void resetTSAndType()

setTSAndType

private void setTSAndType(long timestamp,
 byte type)

sameAsPreviousTSAndType

private boolean sameAsPreviousTSAndType(long timestamp,
 byte type)

isExpired

private boolean isExpired(long timestamp)

getColumnHint

public ColumnCount getColumnHint()

Used by matcher and scan/get to get a hint of the next column to seek to after checkColumn() returns SKIP. Returns the next interesting column we want, or NULL there is none (wildcard scanner).

Specified by:

getColumnHint in interface ColumnTracker

Returns:

The column count.

done

public boolean done()

We can never know a-priori if we are done, so always return false.

Specified by:

done in interface ColumnTracker

getNextRowOrNextColumn

public ScanQueryMatcher.MatchCode getNextRowOrNextColumn(Cell cell)

Description copied from interface: ColumnTracker

Retrieve the MatchCode for the next row or column

Specified by:

getNextRowOrNextColumn in interface ColumnTracker

beforeShipped

public void beforeShipped()

Description copied from interface: ShipperListener

The action that needs to be performed before Shipper.shipped() is performed

Specified by:

beforeShipped in interface ShipperListener

isDone

public boolean isDone(long timestamp)

Description copied from interface: ColumnTracker

Give the tracker a chance to declare it's done based on only the timestamp to allow an early out.

Specified by:

isDone in interface ColumnTracker

Returns:

true to early out based on timestamp.