FlinkMetadata.UniqueGroups (Flink : 2.0-SNAPSHOT API)

All Superinterfaces:

org.apache.calcite.rel.metadata.Metadata

Enclosing class:

FlinkMetadata
```
public static interface FlinkMetadata.UniqueGroups
extends org.apache.calcite.rel.metadata.Metadata
```
Metadata about the (minimum) unique groups of the given columns from a specified relational expression.

Nested Class Summary

Nested Classes
Modifier and Type Interface Description

static interface FlinkMetadata.UniqueGroups.Handler
Handler API.

Field Summary

Fields
Modifier and Type Field Description

static org.apache.calcite.rel.metadata.MetadataDef<FlinkMetadata.UniqueGroups> DEF

static Method METHOD

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`org.apache.calcite.util.ImmutableBitSet`	`getUniqueGroups(org.apache.calcite.util.ImmutableBitSet columns)`	Returns the (minimum) unique groups of the given columns from a specified relational expression.

Methods inherited from interface org.apache.calcite.rel.metadata.Metadata
rel

- Field Detail
  - METHOD
```
static final Method METHOD
```
  - DEF
```
static final org.apache.calcite.rel.metadata.MetadataDef<FlinkMetadata.UniqueGroups> DEF
```
- Method Detail
  - getUniqueGroups
```
org.apache.calcite.util.ImmutableBitSet getUniqueGroups(org.apache.calcite.util.ImmutableBitSet columns)
```
    Returns the (minimum) unique groups of the given columns from a specified relational expression.
    
    Parameters:
    
    columns - the given columns in a specified relational expression. The given columns should not be null.
    
    Returns:
    
    the (minimum) unique columns which should be a sub-collection of the given columns, and should not be null or empty. If none unique columns can be found, return the given columns.