Struct Constraints

pub struct Constraints {
    pub lower: Vec<(Antichain<Timestamp>, Reason)>,
    pub upper: Vec<(Antichain<Timestamp>, Reason)>,
}

Constraints expressed on the timestamp of a query.

The constraints are expressed on the minimum and maximum values, resulting in a (possibly empty) interval of valid timestamps.

The constraints may be redundant, in the interest of providing more complete explanations, but they may also be minimized at any point without altering their behavior by removing redundant constraints.

When combined with a Preference one can determine an ideal timestamp to use.

Fields

lower: Vec<(Antichain<Timestamp>, Reason)>

Timestamps and reasons that impose an inclusive lower bound.

upper: Vec<(Antichain<Timestamp>, Reason)>

Timestamps and reasons that impose an inclusive upper bound.

Implementations

impl Constraints

pub fn minimize(&mut self)

Remove constraints that are dominated by other constraints.

This removes redundant constraints, without removing constraints that are “tight” in the sense that the interval would be meaningfully different without them. For example, two constraints at the same time will both be retained, in the interest of full information. But a lower bound constraint at time t will be removed if there is a constraint at time t + 1 (or any larger time).

pub fn lower_bound(&self) -> Antichain<Timestamp>

An antichain equal to the least upper bound of lower bounds.

pub fn upper_bound(&self) -> Antichain<Timestamp>

An antichain equal to the greatest lower bound of upper bounds.

Trait Implementations

impl Clone for Constraints

fn clone(&self) -> Constraints

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for Constraints

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

Formats the value using the given formatter.

impl Default for Constraints

fn default() -> Constraints

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for Constraints

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl DisplayableInTimeline for Constraints

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

fn display<'a>( &'a self, timeline: Option<&'a Timeline>, ) -> DisplayInTimeline<'a, Self>

impl Serialize for Constraints

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.