Package dev.frostlake.functions

Class AggregateFunction

java.lang.Object

dev.frostlake.functions.BuiltInFunction

dev.frostlake.functions.AggregateFunction

Direct Known Subclasses:

AnyValue, ApproxCountDistinct, ApproxPercentile, ApproxPercentileAccumulate, ApproxPercentileCombine, ApproxTopK, ApproxTopKAccumulate, ApproxTopKCombine, ArrayAgg, ArrayUnionAgg, ArrayUniqueAgg, Avg, BitAndAgg, BitOrAgg, BitXorAgg, BooleanAggregate, Corr, Count, CountIf, CovarPop, CovarSamp, HashAgg, Kurtosis, ListAgg, Max, MaxBy, Median, Min, MinBy, Mode, ObjectAgg, PercentileCont, PercentileDisc, RegrAvgx, RegrAvgy, RegrCount, RegrIntercept, RegrR2, RegrSlope, RegrSxx, RegrSxy, RegrSyy, Skew, StdDev, StdDevPop, StdDevSamp, Sum, Variance, VarPop, VarSamp, VectorAvg, VectorMax, VectorMin, VectorSum

public abstract class AggregateFunction
extends BuiltInFunction

Base class for aggregate functions (SUM, COUNT, LISTAGG, …). An aggregate is a BuiltInFunction whose per-group state lives in an AggregateFunction.Accumulator: the executor creates one accumulator per group, folds every input value into it, and reads the group's result from it at the end. BuiltInFunction.evaluate(java.util.List<java.lang.Object>) is therefore not the aggregation path, and implementations typically return null from it.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
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.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	AggregateFunction(String name, DataType returnType)	Names the aggregate and fixes its declared result type.

Method Summary

Modifier and Type	Method	Description
abstract AggregateFunction.Accumulator	createAccumulator()	Creates the fresh, empty per-group state for one evaluation of this aggregate; the executor makes one per group (or per window partition) and never shares them.

Methods inherited from class dev.frostlake.functions.BuiltInFunction

approximateRejection, binaryRejection, booleanRejection, evaluate, evaluate, fileRejection, geoRejection, getMaxArgCount, getMinArgCount, getName, getReturnType, isVariadic, refusesMissingArgumentsByType, semiStructuredRejection, structuredRejection, temporalRejection, temporalRejection, temporalRejection, textRejection, uuidRejection, vectorRejection

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

AggregateFunction

protected AggregateFunction(String name,
 DataType returnType)

Names the aggregate and fixes its declared result type.

Parameters:

name - the SQL name the aggregate is registered under

returnType - the declared type of the aggregate's result

Method Details

createAccumulator

public abstract AggregateFunction.Accumulator createAccumulator()

Creates the fresh, empty per-group state for one evaluation of this aggregate; the executor makes one per group (or per window partition) and never shares them.

Returns:

a new accumulator starting from this aggregate's empty-group state