ImperativeAggregate Expressions¶

ImperativeAggregate is an extension of the AggregateFunction abstraction for aggregate functions that are expressed using imperative initialize, merge and update methods (that operate on Row-based aggregation buffers).

Contract (Subset)¶

initialize¶

initialize(
  mutableAggBuffer: InternalRow): Unit

Used when:

• EliminateAggregateFilter logical optimization is executed
• AggregatingAccumulator is requested to createBuffer
• AggregationIterator is requested to initializeBuffer
• ObjectAggregationIterator is requested to initAggregationBuffer
• TungstenAggregationIterator is requested to createNewAggregationBuffer
• AggregateProcessor is requested to initialize

merge¶

merge(
  mutableAggBuffer: InternalRow,
  inputAggBuffer: InternalRow): Unit

Used when:

• AggregatingAccumulator is requested to merge
• AggregationIterator is requested to generateProcessRow

update¶

update(
  mutableAggBuffer: InternalRow,
  inputRow: InternalRow): Unit

Used when:

• AggregatingAccumulator is requested to add a value
• AggregationIterator is requested to generateProcessRow
• AggregateProcessor is requested to update

Implementations¶

• HyperLogLogPlusPlus
• PivotFirst
• ScalaUDAF
• TypedImperativeAggregate

CodegenFallback¶

ImperativeAggregate is a CodegenFallback.