Package org.apache.druid.query.groupby.epinephelinae

Class DictionaryBuildingUtils

java.lang.Object

org.apache.druid.query.groupby.epinephelinae.DictionaryBuildingUtils

public class DictionaryBuildingUtils
extends Object

Utilities for parts of the groupBy engine that need to build dictionaries.

Constructor Summary

Constructors

Constructor	Description
DictionaryBuildingUtils()

Method Summary

Modifier and Type	Method	Description
static <T> List<T>	createDictionary()	Creates a forward dictionary (dictionary ID -> value).
static <T> it.unimi.dsi.fastutil.objects.Object2IntMap<T>	createReverseDictionary(it.unimi.dsi.fastutil.Hash.Strategy<T> hashStrategy)	Create reverse dictionary (value -> dictionary ID) that relies on the given Hash.Strategy for hashing and comparing equality.
static int	estimateEntryFootprint(int valueFootprint)	Estimated footprint of a new entry.

Methods inherited from class java.lang.Object

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

Constructor Details

DictionaryBuildingUtils

public DictionaryBuildingUtils()

Method Details

createDictionary

public static <T> List<T> createDictionary()

Creates a forward dictionary (dictionary ID -> value).

createReverseDictionary

public static <T>
it.unimi.dsi.fastutil.objects.Object2IntMap<T> createReverseDictionary(it.unimi.dsi.fastutil.Hash.Strategy<T> hashStrategy)

Create reverse dictionary (value -> dictionary ID) that relies on the given Hash.Strategy for hashing and comparing equality. It explicitly requires a hashing strategy, so that callers are aware of the correct implementation of the .hashCode and the .equals method used to store and address the objects If a value is not present in the reverse dictionary, Object2IntFunction.getInt(java.lang.Object) will return DimensionDictionary.ABSENT_VALUE_ID. The object's NullableTypeStrategy is often enough to create a reverse dictionary for those objects

estimateEntryFootprint

public static int estimateEntryFootprint(int valueFootprint)

Estimated footprint of a new entry.