io.druid.query.extraction

Class MatchingDimExtractionFn

java.lang.Object

io.druid.query.extraction.MatchingDimExtractionFn

All Implemented Interfaces:

DimExtractionFn

public class MatchingDimExtractionFn
extends Object
implements DimExtractionFn

Constructor Summary

Constructors

Constructor and Description
MatchingDimExtractionFn(String expr)

Method Summary

Methods

Modifier and Type	Method and Description
String	apply(String dimValue) The "extraction" function.
byte[]	getCacheKey() Returns a byte[] unique to all concrete implementations of DimExtractionFn.
String	getExpr()
boolean	preservesOrdering() Offers information on whether the extraction will preserve the original ordering of the values.
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

MatchingDimExtractionFn

public MatchingDimExtractionFn(String expr)

Method Detail

getCacheKey

public byte[] getCacheKey()

Description copied from interface: DimExtractionFn

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

Specified by:

getCacheKey in interface DimExtractionFn

Returns:

a byte[] unit to all concrete implements of DimExtractionFn

apply

public String apply(String dimValue)

Description copied from interface: DimExtractionFn

The "extraction" function. This should map a dimension value into some other value. In order to maintain the "null and empty string are equivalent" semantics that Druid provides, the empty string is considered invalid output for this method and should instead return null. This is a contract on the method rather than enforced at a lower level in order to eliminate a global check for extraction functions that do not already need one.

Specified by:

apply in interface DimExtractionFn

Parameters:

dimValue - the original value of the dimension

Returns:

a value that should be used instead of the original

getExpr

public String getExpr()

preservesOrdering

public boolean preservesOrdering()

Description copied from interface: DimExtractionFn

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.

Specified by:

preservesOrdering in interface DimExtractionFn

Returns:

true if ordering is preserved, false otherwise

toString

public String toString()

Overrides:

toString in class Object