RelBuilder.GroupKey (Flink : 2.0-preview1 API)

Enclosing class:

RelBuilder
```
public static interface RelBuilder.GroupKey
```
Information necessary to create the GROUP BY clause of an Aggregate.

See Also:

RelBuilder.groupKey()

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`RelBuilder.GroupKey`	`alias(@Nullable String alias)`	Assigns an alias to this group key.
`int`	`groupKeyCount()`	Returns the number of columns in the group key.

- Method Detail
  - alias
```
RelBuilder.GroupKey alias(@Nullable String alias)
```
    Assigns an alias to this group key.
    Used to assign field names in the group operation.
  - groupKeyCount
```
int groupKeyCount()
```
    Returns the number of columns in the group key.