Package org.apache.calcite.rel.metadata

Interface BuiltInMetadata.Parallelism

All Superinterfaces:
Metadata
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 final MetadataDef<BuiltInMetadata.Parallelism>
    DEF
     

  • Method Summary

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

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

    rel

  • Field Details

  • Method Details

    • isPhaseTransition

      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

      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.