Function try_push_input

datafusion/optimizer/src/extract_leaf_expressions.rs:750–758

Attempts to push a projection's extractable expressions further down. Returns `Some(new_subtree)` if the projection was pushed down or merged, `None` if there is nothing to push or the projection sits above a barrier.

(
    input: &LogicalPlan,
    alias_generator: &Arc<AliasGenerator>,
)

/// Returns `Some(new_subtree)` if the projection was pushed down or merged,
/// `None` if there is nothing to push or the projection sits above a barrier.
fn try_push_input(
    input: &LogicalPlan,
    alias_generator: &Arc<AliasGenerator>,
) -> Result<Option<LogicalPlan>> {
    let LogicalPlan::Projection(proj) = input else {
        return Ok(None);
    };
    split_and_push_projection(proj, alias_generator)
}

/// Splits a projection into extractable pieces, pushes them towards leaf
/// nodes, and adds a recovery projection if needed.