Enum datafusion_expr::Volatility

pub enum Volatility {
    Immutable,
    Stable,
    Volatile,
}

A function’s volatility, which defines the functions eligibility for certain optimizations

Variants

Immutable

Immutable - An immutable function will always return the same output when given the same input. An example of this is super::BuiltinScalarFunction::Cos.

Stable

Stable - A stable function may return different values given the same input across different queries but must return the same value for a given input within a query. An example of this is super::BuiltinScalarFunction::Now.

Volatile

Volatile - A volatile function may change the return value from evaluation to evaluation. Multiple invocations of a volatile function may return different results when used in the same query. An example of this is super::BuiltinScalarFunction::Random.

Trait Implementations

impl Clone for Volatility

fn clone(&self) -> Volatility

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for Volatility

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

Formats the value using the given formatter.

impl Hash for Volatility

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)where
    H: Hasher,
    Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Ord for Volatility

fn cmp(&self, other: &Volatility) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Selfwhere
    Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Selfwhere
    Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Selfwhere
    Self: Sized + PartialOrd<Self>,

Restrict a value to a certain interval.

impl PartialEq<Volatility> for Volatility

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

This method tests for self and other values to be equal, and is used by ==.

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

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

impl PartialOrd<Volatility> for Volatility

fn partial_cmp(&self, other: &Volatility) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

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

This method tests less than (for self and other) and is used by the < operator.

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

This method tests less than or equal to (for self and other) and is used by the <= operator.

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

This method tests greater than (for self and other) and is used by the > operator.

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

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl Copy for Volatility

impl Eq for Volatility

impl StructuralEq for Volatility

impl StructuralPartialEq for Volatility