org.apache.hadoop.hbase.coprocessor.example

Class ScanModifyingObserver

java.lang.Object

org.apache.hadoop.hbase.coprocessor.example.ScanModifyingObserver

All Implemented Interfaces:

Coprocessor, RegionCoprocessor, RegionObserver

@InterfaceAudience.Private
public class ScanModifyingObserver
extends Object
implements RegionCoprocessor, RegionObserver

A RegionObserver which modifies incoming Scan requests to include additional columns than what the user actually requested.

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.hadoop.hbase.Coprocessor

Coprocessor.State

Nested classes/interfaces inherited from interface org.apache.hadoop.hbase.coprocessor.RegionObserver

RegionObserver.MutationType

Field Summary

Fields

Modifier and Type	Field and Description
static String	FAMILY_TO_ADD_KEY
static String	QUALIFIER_TO_ADD_KEY

Fields inherited from interface org.apache.hadoop.hbase.Coprocessor

PRIORITY_HIGHEST, PRIORITY_LOWEST, PRIORITY_SYSTEM, PRIORITY_USER, VERSION

Constructor Summary

Constructors

Constructor and Description
ScanModifyingObserver()

Method Summary

Modifier and Type	Method and Description
Optional<RegionObserver>	getRegionObserver()
void	preScannerOpen(ObserverContext<RegionCoprocessorEnvironment> c, Scan scan) Called before the client opens a new scanner.
void	start(CoprocessorEnvironment env) Called by the CoprocessorEnvironment during it's own startup to initialize the coprocessor.

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.coprocessor.RegionCoprocessor

getBulkLoadObserver, getEndpointObserver

Methods inherited from interface org.apache.hadoop.hbase.Coprocessor

getServices, stop

Methods inherited from interface org.apache.hadoop.hbase.coprocessor.RegionObserver

postAppend, postBatchMutate, postBatchMutateIndispensably, postBulkLoadHFile, postCheckAndDelete, postCheckAndPut, postClose, postCloseRegionOperation, postCommitStoreFile, postCompact, postCompactSelection, postDelete, postExists, postFlush, postFlush, postGetOp, postIncrement, postInstantiateDeleteTracker, postMemStoreCompaction, postMutationBeforeWAL, postOpen, postPut, postReplayWALs, postScannerClose, postScannerFilterRow, postScannerNext, postScannerOpen, postStartRegionOperation, postStoreFileReaderOpen, postWALRestore, preAppend, preAppendAfterRowLock, preBatchMutate, preBulkLoadHFile, preCheckAndDelete, preCheckAndDeleteAfterRowLock, preCheckAndPut, preCheckAndPutAfterRowLock, preClose, preCommitStoreFile, preCompact, preCompactScannerOpen, preCompactSelection, preDelete, preExists, preFlush, preFlush, preFlushScannerOpen, preGetOp, preIncrement, preIncrementAfterRowLock, preMemStoreCompaction, preMemStoreCompactionCompact, preMemStoreCompactionCompactScannerOpen, preOpen, prePrepareTimeStampForDeleteVersion, prePut, preReplayWALs, preScannerClose, preScannerNext, preStoreFileReaderOpen, preStoreScannerOpen, preWALRestore

Field Detail

FAMILY_TO_ADD_KEY

public static final String FAMILY_TO_ADD_KEY

See Also:

Constant Field Values

QUALIFIER_TO_ADD_KEY

public static final String QUALIFIER_TO_ADD_KEY

See Also:

Constant Field Values

Constructor Detail

ScanModifyingObserver

public ScanModifyingObserver()

Method Detail

start

public void start(CoprocessorEnvironment env)
           throws IOException

Description copied from interface: Coprocessor

Called by the CoprocessorEnvironment during it's own startup to initialize the coprocessor.

Specified by:

start in interface Coprocessor

Throws:

IOException

getRegionObserver

public Optional<RegionObserver> getRegionObserver()

Specified by:

getRegionObserver in interface RegionCoprocessor

preScannerOpen

public void preScannerOpen(ObserverContext<RegionCoprocessorEnvironment> c,
                           Scan scan)
                    throws IOException

Description copied from interface: RegionObserver

Called before the client opens a new scanner.

Note: Do not retain references to any Cells returned by scanner, beyond the life of this invocation. If need a Cell reference for later use, copy the cell and use that.

Specified by:

preScannerOpen in interface RegionObserver

Parameters:

c - the environment provided by the region server

scan - the Scan specification

Throws:

IOException