DictionaryBuildingUtils (druid-processing 30.0.1 API)

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

All Methods Static Methods Concrete Methods
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 Detail
  - DictionaryBuildingUtils
```
public DictionaryBuildingUtils()
```
- Method Detail
  - 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.