BuiltInMetadata.ExpressionLineage (Apache Calcite API)

All Superinterfaces:

Metadata

All Known Subinterfaces:

BuiltInMetadata.All

Enclosing class:

BuiltInMetadata
```
public static interface BuiltInMetadata.ExpressionLineage
extends Metadata
```
Metadata about the origins of expressions.

Nested Class Summary

Nested Classes
Modifier and Type Interface Description

static interface BuiltInMetadata.ExpressionLineage.Handler
Handler API.

Field Summary

Fields
Modifier and Type Field Description

static MetadataDef<BuiltInMetadata.ExpressionLineage> DEF

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`java.util.Set<RexNode>`	`getExpressionLineage(RexNode expression)`	Given the input expression applied on the given `RelNode`, this provider returns the expression with its lineage resolved.

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

- Field Detail
  - DEF
```
static final MetadataDef<BuiltInMetadata.ExpressionLineage> DEF
```
- Method Detail
  - getExpressionLineage
```
java.util.Set<RexNode> getExpressionLineage(RexNode expression)
```
    Given the input expression applied on the given RelNode, this provider returns the expression with its lineage resolved.
    In particular, the result will be a set of nodes which might contain references to columns in TableScan operators (RexTableInputRef). An expression can have more than one lineage expression due to Union operators. However, we do not check column equality in Filter predicates. Each TableScan operator below the node is identified uniquely by its qualified name and its entity number.
    For example, if the expression is $0 + 2 and $0 originated from column $3 in the 0 occurrence of table A in the plan, result will be: A.#0.$3 + 2. Occurrences are generated in no particular order, but it is guaranteed that if two expressions referred to the same table, the qualified name + occurrence will be the same.
    
    Parameters:
    
    expression - expression whose lineage we want to resolve
    
    Returns:
    
    set of expressions with lineage resolved, or null if this information cannot be determined (e.g. origin of an expression is an aggregation in an Aggregate operator)