Package dev.frostlake.functions

Interface AggregateFunction.Accumulator

All Known Implementing Classes:
AnyValueAccumulator, ApproxPercentileAccumulator, ApproxTopKAccumulator, ApproxTopKCombineAccumulator, ApproxTopKStateAccumulator, ArrayAggAccumulator, ArrayUnionAggAccumulator, ArrayUniqueAggAccumulator, AvgAccumulator, BitAndAccumulator, BitOrAccumulator, BitXorAccumulator, BoolAndAccumulator, BoolOrAccumulator, BoolXorAccumulator, CorrAccumulator, CountAccumulator, CountIfAccumulator, CovarAccumulator, HashAggAccumulator, HllAccumulator, KurtosisAccumulator, ListAggAccumulator, MaxAccumulator, MaxByMinByAccumulator, MedianAccumulator, MinAccumulator, ModeAccumulator, ObjectAggAccumulator, PercentileContAccumulator, PercentileDigestAccumulator, PercentileDigestCombineAccumulator, PercentileDiscAccumulator, RegrAccumulator, SkewAccumulator, StdDevAccumulator, StdDevPopAccumulator, SumAccumulator, VarianceAccumulator, VarPopAccumulator, VectorAggregateAccumulator
Enclosing class:
AggregateFunction
public static interface AggregateFunction.Accumulator
The running state of one aggregate over one group: values are folded in one row at a time and the group's result is read out at the end. Implementations ignore SQL NULL inputs where Snowflake's aggregates do, and define the empty-group result (NULL for most, 0 for the counting family).

THIS ONE STAYS NESTED, deliberately, against the house rule that interfaces live in their own file. It means nothing away from its owner — an "accumulator" with no aggregate to accumulate for is not a concept — which is the same reason the JDK keeps Map.Entry where it is. Moving it would rename a type 43 files implement, including the frostlake-ai pack's aggregates, for no gain beyond the letter of the rule. The nested-type Checkstyle rule cannot see it either way: an interface nested in a class is implicitly static and never writes the keyword the rule keys on.

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    accumulate(Object value)
    Folds one row's argument value into the running state.
    Object
    getResult()
    The aggregate's result over everything accumulated so far.
    void
    merge(AggregateFunction.Accumulator other)
    Folds another accumulator's state into this one, combining two partial aggregations of the same group.
    void
    reset()
    Clears the state back to the empty-group starting point so the accumulator can be reused.

  • Method Details

    • accumulate

      void accumulate(Object value)
      Folds one row's argument value into the running state.
      Parameters:
      value - the aggregate argument's value for one row; SQL NULL arrives as null

    • getResult

      Object getResult()
      The aggregate's result over everything accumulated so far.
      Returns:
      the group's result, or null where the aggregate defines an empty group as NULL

    • reset

      void reset()
      Clears the state back to the empty-group starting point so the accumulator can be reused.

    • merge

      void merge(AggregateFunction.Accumulator other)
      Folds another accumulator's state into this one, combining two partial aggregations of the same group.
      Parameters:
      other - a partial state of the same aggregate implementation