Enum Monotonicity

pub enum Monotonicity {
    Constant,
    NonDecreasing,
    NonIncreasing,
    Unknown,
}

Represents the monotonicity of a column.

Monotonicity is a property of the output column of stream node that describes the the order of the values in the column. One Monotonicity value is associated with one column, so each stream node should have a MonotonicityMap to describe the monotonicity of all its output columns.

For operator that yields append-only stream, the monotonicity being NonDecreasing means that it will never yield a row smaller than any previously yielded row.

For operator that yields non-append-only stream, the monotonicity being NonDecreasing means that it will never yield a change that has smaller value than any previously yielded change, ignoring the Op. So if such operator yields a NonDecreasing column, Delete and UpdateDeletes can only happen on the last emitted row (or last rows with the same value on the column). This is especially useful for StreamNow operator with UpdateCurrent mode, in which case only one output row is actively maintained and the value is non-decreasing.

Monotonicity property is be considered in default order type, i.e., ASC NULLS LAST. This means that NULLs are considered largest when analyzing monotonicity.

For distributed operators, the monotonicity describes the property of the output column of each shard of the operator.

Variants

Constant

NonDecreasing

NonIncreasing

Unknown

Implementations

impl Monotonicity

pub fn is_constant(self) -> bool

pub fn is_non_decreasing(self) -> bool

pub fn is_non_increasing(self) -> bool

pub fn is_unknown(self) -> bool

pub fn inverse(self) -> Self

Trait Implementations

impl Clone for Monotonicity

fn clone(&self) -> Monotonicity

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for Monotonicity

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

Formats the value using the given formatter.

impl Hash for Monotonicity

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 PartialEq for Monotonicity

fn eq(&self, other: &Monotonicity) -> 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 Monotonicity

impl Eq for Monotonicity

impl StructuralPartialEq for Monotonicity