io.druid.query.extraction

Class LowerExtractionFn

java.lang.Object

io.druid.query.extraction.DimExtractionFn

io.druid.query.extraction.LowerExtractionFn

All Implemented Interfaces:

ExtractionFn

public class LowerExtractionFn
extends DimExtractionFn

Nested Class Summary

Nested classes/interfaces inherited from interface io.druid.query.extraction.ExtractionFn

ExtractionFn.ExtractionType

Constructor Summary

Constructors

Constructor and Description
LowerExtractionFn(String localeString)

Method Summary

Modifier and Type	Method and Description
String	apply(String key) The "extraction" function.
byte[]	getCacheKey() Returns a byte[] unique to all concrete implementations of DimExtractionFn.
ExtractionFn.ExtractionType	getExtractionType() A dim extraction can be of one of two types, renaming or rebucketing.
boolean	preservesOrdering() Offers information on whether the extraction will preserve the original ordering of the values.

Methods inherited from class io.druid.query.extraction.DimExtractionFn

apply, apply

Methods inherited from class java.lang.Object

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

Constructor Detail

LowerExtractionFn

public LowerExtractionFn(String localeString)

Method Detail

apply

@Nullable
public String apply(String key)

Description copied from interface: ExtractionFn

The "extraction" function. This should map a String value into some other String value.

Like ExtractionFn.apply(Object), the empty string is considered invalid output for this method and it should instead return null.

Parameters:

key - string input of extraction function

Returns:

new string with all of the characters in key as an lower case or null if key is empty or null

preservesOrdering

public boolean preservesOrdering()

Description copied from interface: ExtractionFn

Offers information on whether the extraction will preserve the original ordering of the values.

Some optimizations of queries is possible if ordering is preserved. Null values *do* count towards ordering.

Returns:

true if ordering is preserved, false otherwise

getExtractionType

public ExtractionFn.ExtractionType getExtractionType()

Description copied from interface: ExtractionFn

A dim extraction can be of one of two types, renaming or rebucketing. In the `ONE_TO_ONE` case, a unique values is modified into another unique value. In the `MANY_TO_ONE` case, there is no longer a 1:1 relation between old dimension value and new dimension value

Returns:

ExtractionFn.ExtractionType declaring what kind of manipulation this function does

getCacheKey

public byte[] getCacheKey()

Description copied from interface: ExtractionFn

Returns a byte[] unique to all concrete implementations of DimExtractionFn. This byte[] is used to generate a cache key for the specific query.

Returns:

a byte[] unit to all concrete implements of DimExtractionFn