io.druid.query.extraction

Class IdentityExtractionFn

java.lang.Object

io.druid.query.extraction.IdentityExtractionFn

All Implemented Interfaces:

Cacheable, ExtractionFn

public class IdentityExtractionFn
extends Object
implements ExtractionFn

Nested Class Summary

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

ExtractionFn.ExtractionType

Method Summary

Modifier and Type	Method and Description
String	apply(long value) The "extraction" function.
String	apply(Object value) The "extraction" function.
String	apply(String value) The "extraction" function.
boolean	equals(Object o)
byte[]	getCacheKey() Get a byte array used as a cache key.
ExtractionFn.ExtractionType	getExtractionType() A dim extraction can be of one of two types, renaming or rebucketing.
static IdentityExtractionFn	getInstance()
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, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Method Detail

getCacheKey

public byte[] getCacheKey()

Description copied from interface: Cacheable

Get a byte array used as a cache key.

Specified by:

getCacheKey in interface Cacheable

Returns:

a cache key

apply

@Nullable
public String apply(@Nullable
                              Object value)

Description copied from interface: ExtractionFn

The "extraction" function. This should map an Object into some String 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 ExtractionFn

Parameters:

value - the original value of the dimension

Returns:

a value that should be used instead of the original

apply

@Nullable
public String apply(@Nullable
                              String value)

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.

Specified by:

apply in interface ExtractionFn

Parameters:

value - the original value of the dimension

Returns:

a value that should be used instead of the original

apply

public String apply(long value)

Description copied from interface: ExtractionFn

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

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

Specified by:

apply in interface ExtractionFn

Parameters:

value - the original value of the dimension

Returns:

a value that should be used instead of the original

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.

Specified by:

preservesOrdering in interface ExtractionFn

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

Specified by:

getExtractionType in interface ExtractionFn

Returns:

ExtractionFn.ExtractionType declaring what kind of manipulation this function does

toString

public String toString()

Overrides:

toString in class Object

equals

public boolean equals(Object o)

Overrides:

equals in class Object

getInstance

public static final IdentityExtractionFn getInstance()