Interface BuiltInMetadata.PopulationSize

  • All Superinterfaces:
    Enclosing class:

    public static interface BuiltInMetadata.PopulationSize
    extends Metadata
    Metadata about the number of distinct values in the original source of a column or set of columns.
    • Method Detail

      • getPopulationSize

        java.lang.Double getPopulationSize​(ImmutableBitSet groupKey)
        Estimates the distinct row count in the original source for the given groupKey, ignoring any filtering being applied by the expression. Typically, "original source" means base table, but for derived columns, the estimate may come from a non-leaf rel such as a LogicalProject.
        groupKey - column mask representing the subset of columns for which the row count will be determined
        distinct row count for the given groupKey, or null if no reliable estimate can be determined