Function mz_transform::dataflow::optimize_dataflow_demand

fn optimize_dataflow_demand(
    dataflow: &mut DataflowDesc
) -> Result<(), TransformError>

Pushes demand information from published outputs to dataflow inputs, projecting away unnecessary columns.

Dataflows that exist for the sake of generating plan explanations do not have published outputs. In this case, we push demand information from views not depended on by other views to dataflow inputs.