Function build_recover_project_plan 

fn build_recover_project_plan(
    schema: &DFSchema,
    input: LogicalPlan,
) -> Result<LogicalPlan>

Build the projection plan to eliminate unnecessary columns produced by the “intermediate” projection plan built in build_common_expr_project_plan.

This is required to keep the schema the same for plans that pass the input on to the output, such as Filter or Sort.