Package dev.frostlake.functions.aggregate

Class ApproxTopKEstimate

java.lang.Object
dev.frostlake.functions.BuiltInFunction
dev.frostlake.functions.aggregate.ApproxTopKEstimate
public class ApproxTopKEstimate extends BuiltInFunction
APPROX_TOP_K_ESTIMATE(state [, k]): the k most frequent [value, count] pairs of an APPROX_TOP_K_ACCUMULATE or APPROX_TOP_K_COMBINE state, as APPROX_TOP_K would list them (k defaults to 1 and is a constant between 1 and 100000, judged at compile time). A NULL state is NULL; an argument that is not a state refuses with Invalid parameter value: ApproxTopK state. Reason: invalid type. The scalar half of the accumulate family, so it lives beside it.

  • Constructor Details

    • ApproxTopKEstimate

      public ApproxTopKEstimate()

  • Method Details

    • evaluate

      public Object evaluate(List<Object> args)
      Description copied from class: BuiltInFunction
      Computes the function's result over its already-evaluated argument values. A SQL NULL argument arrives as Java null, and returning null makes the SQL result NULL.
      Specified by:
      evaluate in class BuiltInFunction
      Parameters:
      args - the argument values, in call order
      Returns:
      the function's value for these arguments, or null for SQL NULL

    • getMinArgCount

      public int getMinArgCount()
      Description copied from class: BuiltInFunction
      The fewest arguments a call to this function may pass; fewer is an argument-count error.
      Specified by:
      getMinArgCount in class BuiltInFunction
      Returns:
      the minimum accepted argument count

    • getMaxArgCount

      public int getMaxArgCount()
      Description copied from class: BuiltInFunction
      The most arguments a call to this function may pass; Integer.MAX_VALUE marks a variadic function (see BuiltInFunction.isVariadic()).
      Specified by:
      getMaxArgCount in class BuiltInFunction
      Returns:
      the maximum accepted argument count