Enum FunctionKind 

pub enum FunctionKind {
    Scalar,
    Aggregate,
    Window,
    Volatile,
}

Function classification — affects resolver behavior and downstream planner cost estimation.

Variants

Scalar

Pure scalar function: same input → same output, no side effects, no row-context dependency. The planner is free to constant-fold or push-down through joins.

Aggregate

Aggregate function: consumes a Vec of input values, produces a single output. Only valid in projection lists / HAVING / window frames.

Window

Window function: like aggregate but evaluates over an ORDER BY frame. Stays in projection lists only.

Volatile

Side-effecting / time-dependent function: NOW(), RANDOM(). The planner cannot cache results across rows.

Trait Implementations

impl Clone for FunctionKind

fn clone(&self) -> FunctionKind

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for FunctionKind

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl PartialEq for FunctionKind

fn eq(&self, other: &FunctionKind) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for FunctionKind

impl Eq for FunctionKind

impl StructuralPartialEq for FunctionKind