Module aggregate_bridge 

DataFusion aggregate bridge for streaming aggregation.

Bridges DataFusion’s Accumulator trait with laminar-core’s DynAccumulator / DynAggregatorFactory traits. This avoids duplicating aggregation logic. DataFusion Aggregate Bridge

Bridges DataFusion’s 50+ built-in aggregate functions into LaminarDB’s DynAccumulator / DynAggregatorFactory traits. This avoids reimplementing statistical functions (STDDEV, VARIANCE, PERCENTILE, etc.) that DataFusion already provides.

Architecture

DataFusion World                 LaminarDB World
┌───────────────────┐           ┌──────────────────────┐
│ AggregateUDF      │           │ DynAggregatorFactory │
│   └─▶ Accumulator │──bridge──▶│   └─▶ DynAccumulator │
│       (ScalarValue)│           │       (ScalarResult) │
└───────────────────┘           └──────────────────────┘

Ring Architecture

This bridge is Ring 1 (allocates, uses dynamic dispatch). Ring 0 workloads continue to use the hand-written static-dispatch aggregators.

Structs

DataFusionAccumulatorAdapter

Adapts a DataFusion datafusion_expr::Accumulator into LaminarDB’s DynAccumulator trait.

DataFusionAggregateFactory

Factory for creating DataFusionAccumulatorAdapter instances.

Functions

create_aggregate_factory

Creates a DataFusionAggregateFactory for a named built-in aggregate.

lookup_aggregate_udf

Looks up a DataFusion built-in aggregate function by name.

result_to_scalar_value

Converts a ScalarResult to a DataFusion ScalarValue.

scalar_value_to_result

Converts a DataFusion ScalarValue to a LaminarDB ScalarResult.