Package org.apache.hadoop.hbase.filter

Class KeyOnlyFilter

java.lang.Object

org.apache.hadoop.hbase.filter.Filter

org.apache.hadoop.hbase.filter.FilterBase

org.apache.hadoop.hbase.filter.KeyOnlyFilter

@Public
public class KeyOnlyFilter
extends FilterBase

A filter that will only return the key component of each KV (the value will be rewritten as empty).

This filter can be used to grab all of the keys without having to also grab the values.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
(package private) static class	KeyOnlyFilter.KeyOnlyByteBufferExtendedCell
(package private) static class	KeyOnlyFilter.KeyOnlyCell

Nested classes/interfaces inherited from class org.apache.hadoop.hbase.filter.Filter

Filter.ReturnCode

Field Summary

Fields

Modifier and Type	Field	Description
(package private) boolean	lenAsVal

Fields inherited from class org.apache.hadoop.hbase.filter.Filter

reversed

Constructor Summary

Constructors

Constructor	Description
KeyOnlyFilter()
KeyOnlyFilter(boolean lenAsVal)

Method Summary

Modifier and Type	Method	Description
(package private) boolean	areSerializedFieldsEqual(Filter o)	Returns true if and only if the fields of the filter that are serialized are equal to the corresponding fields in other.
static Filter	createFilterFromArguments(ArrayList<byte[]> filterArguments)
private Cell	createKeyOnlyCell(Cell c)
boolean	equals(Object obj)
Filter.ReturnCode	filterCell(Cell ignored)	A way to filter based on the column family, column qualifier and/or the column value.
boolean	filterRowKey(Cell cell)	Filters a row based on the row key.
int	hashCode()
static KeyOnlyFilter	parseFrom(byte[] pbBytes)	Parse a serialized representation of KeyOnlyFilter
byte[]	toByteArray()	Returns The filter serialized using pb
Cell	transformCell(Cell cell)	By default no transformation takes place By default no transformation takes place Give the filter a chance to transform the passed Cell.

Methods inherited from class org.apache.hadoop.hbase.filter.FilterBase

filterAllRemaining, filterRow, filterRowCells, getNextCellHint, hasFilterRow, isFamilyEssential, reset, toString

Methods inherited from class org.apache.hadoop.hbase.filter.Filter

isReversed, setReversed

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Details

lenAsVal

boolean lenAsVal

Constructor Details

KeyOnlyFilter

public KeyOnlyFilter()

KeyOnlyFilter

public KeyOnlyFilter(boolean lenAsVal)

Method Details

filterRowKey

public boolean filterRowKey(Cell cell)
                     throws IOException

Description copied from class: Filter

Filters a row based on the row key. If this returns true, the entire row will be excluded. If false, each KeyValue in the row will be passed to Filter.filterCell(Cell) below. If Filter.filterAllRemaining() returns true, then Filter.filterRowKey(Cell) should also return true. Concrete implementers can signal a failure condition in their code by throwing an IOException.

Overrides:

filterRowKey in class FilterBase

Parameters:

cell - The first cell coming in the new row

Returns:

true, remove entire row, false, include the row (maybe).

Throws:

IOException - in case an I/O or an filter specific failure needs to be signaled.

transformCell

public Cell transformCell(Cell cell)

Description copied from class: FilterBase

By default no transformation takes place Give the filter a chance to transform the passed Cell. If the Cell is changed a new Cell object must be returned.

NOTICE: Filter will be evaluate at server side so the returned Cell must be an ExtendedCell, although it is marked as IA.Private.

Overrides:

transformCell in class FilterBase

Parameters:

cell - the Cell in question

Returns:

the changed Cell

See Also:

• The transformed KeyValue is what is eventually returned to the client. Most filters will return the passed KeyValue unchanged.
• for an example of a transformation. Concrete implementers can signal a failure condition in their code by throwing an IOException.

createKeyOnlyCell

private Cell createKeyOnlyCell(Cell c)

filterCell

public Filter.ReturnCode filterCell(Cell ignored)
                             throws IOException

Description copied from class: Filter

A way to filter based on the column family, column qualifier and/or the column value. Return code is described below. This allows filters to filter only certain number of columns, then terminate without matching ever column. If filterRowKey returns true, filterCell needs to be consistent with it. filterCell can assume that filterRowKey has already been called for the row. If your filter returns ReturnCode.NEXT_ROW, it should return ReturnCode.NEXT_ROW until Filter.reset() is called just in case the caller calls for the next row. Concrete implementers can signal a failure condition in their code by throwing an IOException.

Overrides:

filterCell in class Filter

Parameters:

ignored - the Cell in question

Returns:

code as described below

Throws:

IOException - in case an I/O or an filter specific failure needs to be signaled.

See Also:

• Filter.ReturnCode

createFilterFromArguments

public static Filter createFilterFromArguments(ArrayList<byte[]> filterArguments)

toByteArray

public byte[] toByteArray()

Returns The filter serialized using pb

Overrides:

toByteArray in class FilterBase

Returns:

The filter serialized using pb

parseFrom

public static KeyOnlyFilter parseFrom(byte[] pbBytes)
                               throws DeserializationException

Parse a serialized representation of KeyOnlyFilter

Parameters:

pbBytes - A pb serialized KeyOnlyFilter instance

Returns:

An instance of KeyOnlyFilter made from bytes

Throws:

DeserializationException - if an error occurred

See Also:

• toByteArray()

areSerializedFieldsEqual

boolean areSerializedFieldsEqual(Filter o)

Returns true if and only if the fields of the filter that are serialized are equal to the corresponding fields in other. Used for testing.

Overrides:

areSerializedFieldsEqual in class FilterBase

Returns:

true if and only if the fields of the filter that are serialized are equal to the corresponding fields in other. Used for testing.

equals

public boolean equals(Object obj)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object