Struct PathKeys 

pub struct PathKeys {
    pub keys: Vec<PathKey>,
}

A list of pathkeys describing a plan operator’s output order. The order is lexicographic: keys[0] is the primary sort key, keys[1] breaks ties, etc.

Fields

keys: Vec<PathKey>

Implementations

impl PathKeys

pub fn unordered() -> PathKeys

Empty pathkeys — the plan operator makes no order guarantee.

pub fn asc(field: FieldRef) -> PathKeys

Single-key pathkeys ordered by field ascending.

pub fn desc(field: FieldRef) -> PathKeys

Single-key pathkeys ordered by field descending.

pub fn is_unordered(&self) -> bool

True when the operator emits rows with no guaranteed order. Consumers that need a specific order must add a Sort node above.

pub fn prefix_match(&self, required: &PathKeys) -> usize

Returns the number of leading pathkeys that match required. Used by the planner to decide whether to emit an incremental sort: if prefix_match returns ≥ 1, the input already satisfies a prefix of the required order and an incremental sort is cheaper than a full sort.

Example:

• self: [a ASC, b ASC]

• required: [a ASC, b ASC, c DESC]

• returns: 2

• self: [a ASC]

• required: [b ASC, a ASC]

• returns: 0 (prefix doesn’t match)

pub fn satisfies(&self, required: &PathKeys) -> bool

True when self fully satisfies required — i.e. self.prefix_match(required) == required.keys.len() AND self has at least as many keys as required. Callers use this to decide whether a Sort node can be elided entirely.

pub fn appended(&self, key: PathKey) -> PathKeys

Append a pathkey, returning a new PathKeys with one more column at the end. Used by the planner when composing pathkeys from an index scan + a tiebreaker.

pub fn truncated(&self, n: usize) -> PathKeys

Truncate to the first n keys. Used when a plan operator only preserves a prefix of its input’s order (e.g. hash aggregation destroys ordering beyond the grouping columns).

pub fn len(&self) -> usize

Number of pathkeys in the list.

pub fn is_empty(&self) -> bool

Is the pathkey list empty?

Trait Implementations

impl Clone for PathKeys

fn clone(&self) -> PathKeys

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for PathKeys

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

Formats the value using the given formatter.

impl Default for PathKeys

fn default() -> PathKeys

Returns the “default value” for a type.

impl PartialEq for PathKeys

fn eq(&self, other: &PathKeys) -> 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 Eq for PathKeys

impl StructuralPartialEq for PathKeys