org.apache.hadoop.hbase.regionserver

Class ScanWildcardColumnTracker

java.lang.Object

org.apache.hadoop.hbase.regionserver.ScanWildcardColumnTracker

All Implemented Interfaces:

ColumnTracker

@InterfaceAudience.Private
public class ScanWildcardColumnTracker
extends Object
implements ColumnTracker

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

Constructor Summary

Constructors

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

Method Summary

Modifier and Type	Method and Description
ScanQueryMatcher.MatchCode	checkColumn(byte[] bytes, int offset, int length, byte type) Checks if the column is present in the list of requested columns by returning the match code instance.
ScanQueryMatcher.MatchCode	checkVersions(byte[] bytes, int offset, int length, 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(byte[] bytes, int offset, int qualLength) 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.
void	reset() Resets the Matcher

Methods inherited from class java.lang.Object

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

Constructor Detail

ScanWildcardColumnTracker

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

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.

Method Detail

checkColumn

public ScanQueryMatcher.MatchCode checkColumn(byte[] bytes,
                                              int offset,
                                              int length,
                                              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(byte[], int, int, 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

type - The type of the KeyValue

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(byte[] bytes,
                                                int offset,
                                                int length,
                                                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 keyvalue needs to be included by calling the ColumnTracker.checkColumn(byte[], int, int, 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(byte[], int, int, 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

timestamp - The timeToLive to enforce.

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.

reset

public void reset()

Description copied from interface: ColumnTracker

Resets the Matcher

Specified by:

reset in interface ColumnTracker

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

Returns:

false

getNextRowOrNextColumn

public ScanQueryMatcher.MatchCode getNextRowOrNextColumn(byte[] bytes,
                                                         int offset,
                                                         int qualLength)

Description copied from interface: ColumnTracker

Retrieve the MatchCode for the next row or column

Specified by:

getNextRowOrNextColumn in interface ColumnTracker

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.