BuiltInMetadata.Parallelism (Apache Calcite API)

All Superinterfaces:

Metadata

All Known Subinterfaces:

BuiltInMetadata.All

Enclosing class:

BuiltInMetadata
```
public static interface BuiltInMetadata.Parallelism
extends Metadata
```
Metadata about the degree of parallelism of a relational expression, and how its operators are assigned to processes with independent resource pools.

Nested Class Summary

Nested Classes
Modifier and Type Interface Description

static interface BuiltInMetadata.Parallelism.Handler
Handler API.

Field Summary

Fields
Modifier and Type Field Description

static MetadataDef<BuiltInMetadata.Parallelism> DEF

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`java.lang.Boolean`	`isPhaseTransition()`	Returns whether each physical operator implementing this relational expression belongs to a different process than its inputs.
`java.lang.Integer`	`splitCount()`	Returns the number of distinct splits of the data.

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

- Field Detail
  - DEF
```
static final MetadataDef<BuiltInMetadata.Parallelism> DEF
```
- Method Detail
  - isPhaseTransition
```
java.lang.Boolean isPhaseTransition()
```
    Returns whether each physical operator implementing this relational expression belongs to a different process than its inputs.
    A collection of operators processing all of the splits of a particular stage in the query pipeline is called a "phase". A phase starts with a leaf node such as a TableScan, or with a phase-change node such as an Exchange. Hadoop's shuffle operator (a form of sort-exchange) causes data to be sent across the network.
  - splitCount
```
java.lang.Integer splitCount()
```
    Returns the number of distinct splits of the data.
    Note that splits must be distinct. For broadcast, where each copy is the same, returns 1.
    Thus the split count is the proportion of the data seen by each operator instance.