DimensionIdCodec (druid-processing 30.0.1 API)

Type Parameters:

DimensionType - Type of the dimension holder
```
public interface DimensionIdCodec<DimensionType>
```
Dimension to integer id encoder - decoder i.e. it is an interface for converters of dimension to dictionary id and back. It only handles single value dimensions. Handle multi-value dimensions (i.e. strings) using the KeyMappingMultiValueGroupByColumnSelectorStrategy.
Encoding
The caller is expected to handle non-null values. Null values must be filtered by the caller, and assigned GroupByColumnSelectorStrategy.GROUP_BY_MISSING_VALUE 1. DimensionIdCodec extracts the dimension from the selector 2. The value gets encoded into a dictionaryId, using lookupId(DimensionType) 3. The callers can use this integer dictionaryID to represent the grouping key
Decoding
Converts back the dictionaryId to the dimension value. The implementations are not expected to handle GroupByColumnSelectorStrategy.GROUP_BY_MISSING_VALUE. The callers should handle those values appropriately ontheir own, and filter those out before trying to convert the dictionary id back to value.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`boolean`	`canCompareIds()`	Returns if the object comparison can be optimised directly by comparing the dictionaryIds, instead of decoding the objects and comparing those.
`DimensionType`	`idToKey(int id)`
`MemoryFootprint<Integer>`	`lookupId(DimensionType dimension)`
`void`	`reset()`

- Method Detail
  - lookupId
```
MemoryFootprint<Integer> lookupId(DimensionType dimension)
```
    Returns:
    
    DictionaryId of the object at the given index and the memory increase associated with it
  - idToKey
```
DimensionType idToKey(int id)
```
  - canCompareIds
```
boolean canCompareIds()
```
    Returns if the object comparison can be optimised directly by comparing the dictionaryIds, instead of decoding the objects and comparing those. Therefore, it returns true iff the "dict" function defined by dict(id) = value is monotonically increasing. Ids backed by dictionaries built on the fly can never be compared, therefore those should always return false.
  - reset
```
void reset()
```