Enum Source 

pub enum Source {
    Sketch,
    Quantile,
    Sample,
    Zone,
    Dictionary,
    Synopsis,
    Propagation,
    Observation,
    Constant,
}

Where an estimate came from.

Printed by EXPLAIN, so these are the words a person reads when a plan went wrong.

Variants

Sketch

A distinct-count sketch, outside the regime where it is exact.

Quantile

A quantile summary, read without its certificate.

Sample

The stored sample.

Zone

A minimum and a maximum, interpolated between.

Dictionary

A dictionary’s size standing in for a distinct count.

Synopsis

A frequency synopsis.

Propagation

A propagation rule over another operator’s statistics.

Observation

Something a previous execution measured, from the observation log.

Constant

A constant in the source. The weakest answer that is not Unknown, and the one worth finding in an EXPLAIN because it means nobody had a number here at all.

Implementations

impl Source

pub const fn name(self) -> &'static str

The word EXPLAIN prints.

Trait Implementations

impl Clone for Source

fn clone(&self) -> Source

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for Source

impl Debug for Source

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

Formats the value using the given formatter.

impl Display for Source

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

Formats the value using the given formatter.

impl Eq for Source

impl Hash for Source

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 Source

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for Source