org.apache.hadoop.hbase.filter

Class FirstKeyOnlyFilter

java.lang.Object

org.apache.hadoop.hbase.filter.Filter

org.apache.hadoop.hbase.filter.FilterBase

org.apache.hadoop.hbase.filter.FirstKeyOnlyFilter

Direct Known Subclasses:

FirstKeyValueMatchingQualifiersFilter

@InterfaceAudience.Public
public class FirstKeyOnlyFilter
extends FilterBase

A filter that will only return the first KV from each row.

This filter can be used to more efficiently perform row count operations.

Nested Class Summary

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

Filter.ReturnCode

Field Summary

Fields

Modifier and Type	Field and Description
private boolean	foundKV

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

reversed

Constructor Summary

Constructors

Constructor and Description
FirstKeyOnlyFilter()

Method Summary

Modifier and Type	Method and Description
(package private) boolean	areSerializedFieldsEqual(Filter o) Default implementation so that writers of custom filters aren't forced to implement.
static Filter	createFilterFromArguments(ArrayList<byte[]> filterArguments)
boolean	equals(Object obj)
Filter.ReturnCode	filterCell(Cell c) A way to filter based on the column family, column qualifier and/or the column value.
Filter.ReturnCode	filterKeyValue(Cell c) Deprecated.
boolean	filterRowKey(Cell cell) Filters a row based on the row key.
protected boolean	hasFoundKV()
int	hashCode()
static FirstKeyOnlyFilter	parseFrom(byte[] pbBytes)
void	reset() Filters that are purely stateless and do nothing in their reset() methods can inherit this null/empty implementation.
protected void	setFoundKV(boolean value)
byte[]	toByteArray() Return length 0 byte array for Filters that don't require special serialization

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

filterAllRemaining, filterRow, filterRowCells, filterRowKey, getNextCellHint, hasFilterRow, isFamilyEssential, toString, transformCell

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 Detail

foundKV

private boolean foundKV

Constructor Detail

FirstKeyOnlyFilter

public FirstKeyOnlyFilter()

Method Detail

reset

public void reset()

Description copied from class: FilterBase

Filters that are purely stateless and do nothing in their reset() methods can inherit this null/empty implementation. Reset the state of the filter between rows. Concrete implementers can signal a failure condition in their code by throwing an IOException.

Overrides:

reset in class FilterBase

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.

filterKeyValue

@Deprecated
public Filter.ReturnCode filterKeyValue(Cell c)

Deprecated.

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, filterKeyValue needs to be consistent with it. filterKeyValue 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:

filterKeyValue in class Filter

Parameters:

c - the Cell in question

Returns:

code as described below, Filter.ReturnCode.INCLUDE by default

See Also:

Filter.ReturnCode

filterCell

public Filter.ReturnCode filterCell(Cell c)

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:

c - the Cell in question

Returns:

code as described below

See Also:

Filter.ReturnCode

createFilterFromArguments

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

hasFoundKV

protected boolean hasFoundKV()

Returns:

true if first KV has been found.

setFoundKV

protected void setFoundKV(boolean value)

Parameters:

value - update foundKV flag with value.

toByteArray

public byte[] toByteArray()

Description copied from class: FilterBase

Return length 0 byte array for Filters that don't require special serialization

Overrides:

toByteArray in class FilterBase

Returns:

The filter serialized using pb

parseFrom

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

Parameters:

pbBytes - A pb serialized FirstKeyOnlyFilter instance

Returns:

An instance of FirstKeyOnlyFilter made from bytes

Throws:

DeserializationException

See Also:

toByteArray()

areSerializedFieldsEqual

boolean areSerializedFieldsEqual(Filter o)

Description copied from class: FilterBase

Default implementation so that writers of custom filters aren't forced to implement.

Overrides:

areSerializedFieldsEqual in class FilterBase

Parameters:

o - the other filter to compare with

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