Package org.apache.druid.java.util.common

Enum Class StringEncoding

java.lang.Object

java.lang.Enum<StringEncoding>

org.apache.druid.java.util.common.StringEncoding

All Implemented Interfaces:

Serializable, Comparable<StringEncoding>, Constable, Cacheable

public enum StringEncoding
extends Enum<StringEncoding>
implements Cacheable

An enum that provides a way for users to specify what encoding should be used when hashing strings. The main reason for this setting's existence is getting the best performance possible. When operating on memory mapped segments -- which store strings as UTF-8 -- it is fastest to use "UTF8". When operating on the result of expressions, or on an in-heap IncrementalIndex -- which use Java strings -- it is fastest to use "UTF16LE". This decision cannot be made locally, because different encodings do not generate equivalent hashes, and therefore they are not mergeable. The decision must be made globally by the end user or by the SQL planner, and should be based on where most input strings are expected to come from. Currently, UTF8 and UTF16LE are the only two options, because there are no situations where other options would be higher-performing.

Nested Class Summary

Nested classes/interfaces inherited from class java.lang.Enum

Enum.EnumDesc<E extends Enum<E>>

Enum Constant Summary

Enum Constants

Enum Constant	Description
UTF16LE
UTF8

Method Summary

Modifier and Type	Method	Description
static StringEncoding	fromString(String name)
byte[]	getCacheKey()	Get a byte array used as a cache key.
String	toString()
static StringEncoding	valueOf(String name)	Returns the enum constant of this class with the specified name.
static StringEncoding[]	values()	Returns an array containing the constants of this enum class, in the order they are declared.

Methods inherited from class java.lang.Enum

clone, compareTo, describeConstable, equals, finalize, getDeclaringClass, hashCode, name, ordinal, valueOf

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Enum Constant Details

UTF8

public static final StringEncoding UTF8

UTF16LE

public static final StringEncoding UTF16LE

Method Details

values

public static StringEncoding[] values()

Returns an array containing the constants of this enum class, in the order they are declared.

Returns:

an array containing the constants of this enum class, in the order they are declared

valueOf

public static StringEncoding valueOf(String name)

Returns the enum constant of this class with the specified name. The string must match exactly an identifier used to declare an enum constant in this class. (Extraneous whitespace characters are not permitted.)

Parameters:

name - the name of the enum constant to be returned.

Returns:

the enum constant with the specified name

Throws:

IllegalArgumentException - if this enum class has no constant with the specified name

NullPointerException - if the argument is null

fromString

public static StringEncoding fromString(String name)

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:

bytes to be used as cache key - or null if this object should not be cached.

toString

public String toString()

Overrides:

toString in class Enum<StringEncoding>