BuiltInMetadata.Selectivity (Apache Calcite API)

All Superinterfaces:

Metadata

All Known Subinterfaces:

BuiltInMetadata.All

Enclosing class:

BuiltInMetadata
```
public static interface BuiltInMetadata.Selectivity
extends Metadata
```
Metadata about the selectivity of a predicate.

Nested Class Summary

Nested Classes
Modifier and Type Interface Description

static interface BuiltInMetadata.Selectivity.Handler
Handler API.

Field Summary

Fields
Modifier and Type Field Description

static MetadataDef<BuiltInMetadata.Selectivity> DEF

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`java.lang.Double`	`getSelectivity(RexNode predicate)`	Estimates the percentage of an expression's output rows which satisfy a given predicate.

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

- Field Detail
  - DEF
```
static final MetadataDef<BuiltInMetadata.Selectivity> DEF
```
- Method Detail
  - getSelectivity
```
java.lang.Double getSelectivity(RexNode predicate)
```
    Estimates the percentage of an expression's output rows which satisfy a given predicate. Returns null to indicate that no reliable estimate can be produced.
    
    Parameters:
    
    predicate - predicate whose selectivity is to be estimated against rel's output
    
    Returns:
    
    estimated selectivity (between 0.0 and 1.0), or null if no reliable estimate can be determined