Push-Based Model¶

Grafeo uses a push-based (producer-driven) execution model.

Push vs Pull¶

Model	Data Flow	Control
Pull (Volcano)	Child -> Parent	Parent requests
Push	Parent -> Child	Parent pushes

Benefits¶

Better pipelining - No function call overhead per row
Parallelism - Natural morsel-driven parallelism
Cache efficiency - Process data while hot
Early termination - LIMIT can stop pipeline early

Pipeline Structure¶

Pipeline 1: Scan -> Filter -> Project -> Exchange
Pipeline 2: Exchange -> Aggregate -> Sink

Morsel-Driven Parallelism¶

Work is divided into morsels (chunks of data):

Thread 1: [Morsel 0] -> [Morsel 4] -> [Morsel 8]
Thread 2: [Morsel 1] -> [Morsel 5] -> [Morsel 9]
Thread 3: [Morsel 2] -> [Morsel 6] -> ...
Thread 4: [Morsel 3] -> [Morsel 7] -> ...