IdMapping (druid-processing 28.0.0 API)

java.lang.Object
- org.apache.druid.segment.IdMapping

```
public class IdMapping
extends Object
```
Map some set of dictionary id to a smaller set of dictionaryIds (or... the same if you are wasteful), providing a translation layer between them

Nested Class Summary

Nested Classes
Modifier and Type Class Description

static class IdMapping.Builder

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`int`	`getForwardedId(int id)`	Get the substitute index, given the original
`int`	`getReverseId(int id)`	Get the original index, given the substitute
`int`	`getValueCardinality()`	Get the number of values stored in `forwardMapping`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Method Detail
  - getForwardedId
```
public int getForwardedId(int id)
```
    Get the substitute index, given the original
  - getReverseId
```
public int getReverseId(int id)
```
    Get the original index, given the substitute
  - getValueCardinality
```
public int getValueCardinality()
```
    Get the number of values stored in forwardMapping