Struct Classes 

pub struct Classes { /* private fields */ }

How many decisions were made on what.

The class histogram of spec/stats/09-measurement.md section 9.5. For a whole suite, the fraction of the planner’s decisions that were exact, certified, estimated or unknown, which is the direct measurement of whether the statistics layer is doing its job. It is more diagnostic than q-error for the first several milestones, because early on the estimates are bad for the boring reason that there are none.

Implementations

impl Classes

pub const fn new() -> Self

An empty histogram.

pub fn record<T>(&mut self, stat: &Stat<T>)

Counts one decision.

pub fn record_class(&mut self, class: Option<Class>)

Counts one decision whose class is already in hand.

pub const fn exact(self) -> u64

Decisions made on an exact number.

pub const fn certified(self) -> u64

Decisions made on a bounded number.

pub const fn estimated(self) -> u64

Decisions made on a guess.

pub const fn unknown(self) -> u64

Decisions made with no number at all.

pub const fn total(self) -> u64

Every decision counted.

pub fn known_share(self) -> f64

The fraction of decisions that had a number of any kind behind them, zero for an empty histogram.

pub fn merge(&mut self, other: Self)

Adds another histogram into this one, for a report that covers a suite rather than a query.

Trait Implementations

impl Clone for Classes

fn clone(&self) -> Classes

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for Classes

impl Debug for Classes

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

Formats the value using the given formatter.

impl Default for Classes

fn default() -> Classes

Returns the “default value” for a type.

impl Display for Classes

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

Formats the value using the given formatter.

impl Eq for Classes

impl PartialEq for Classes

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for Classes