BuiltInMetadata.ColumnOrigin (Apache Calcite API)

All Superinterfaces:

Metadata

All Known Subinterfaces:

BuiltInMetadata.All

Enclosing class:

BuiltInMetadata
```
public static interface BuiltInMetadata.ColumnOrigin
extends Metadata
```
Metadata about the origins of columns.

Nested Class Summary

Nested Classes
Modifier and Type Interface Description

static interface BuiltInMetadata.ColumnOrigin.Handler
Handler API.

Field Summary

Fields
Modifier and Type Field Description

static MetadataDef<BuiltInMetadata.ColumnOrigin> DEF

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`java.util.Set<RelColumnOrigin>`	`getColumnOrigins(int outputColumn)`	For a given output column of an expression, determines all columns of underlying tables which contribute to result values.

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

- Field Detail
  - DEF
```
static final MetadataDef<BuiltInMetadata.ColumnOrigin> DEF
```
- Method Detail
  - getColumnOrigins
```
java.util.Set<RelColumnOrigin> getColumnOrigins(int outputColumn)
```
    For a given output column of an expression, determines all columns of underlying tables which contribute to result values. An output column may have more than one origin due to expressions such as Union and LogicalProject. The optimizer may use this information for catalog access (e.g. index availability).
    
    Parameters:
    
    outputColumn - 0-based ordinal for output column of interest
    
    Returns:
    
    set of origin columns, or null if this information cannot be determined (whereas empty set indicates definitely no origin columns at all)