Skip to content

DeclarativeAggregate Expression-Based Functions

DeclarativeAggregate is an extension of the AggregateFunction abstraction for Catalyst Expression-based aggregate functions that use Catalyst Expression for evaluation.

DeclarativeAggregate is an Unevaluable.

Contract

evaluateExpression

evaluateExpression: Expression

Catalyst Expression to calculate the final value of this aggregate function

Used when:

Expressions to Initialize Empty Aggregation Buffers

initialValues: Seq[Expression]

Catalyst Expressions to initialize empty aggregation buffers (for the initial values of this aggregate function)

Used when:

mergeExpressions

mergeExpressions: Seq[Expression]

Catalyst Expressions to...FIXME

updateExpressions

updateExpressions: Seq[Expression]

Catalyst Expressions to update the mutable aggregation buffer based on an input row

Used when:

Implementations