Interface BuiltInMetadata.Parallelism

  • All Superinterfaces:
    All Known Subinterfaces:
    Enclosing class:

    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.
    • 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.