Struct MostCommonValues 

pub struct MostCommonValues {
    pub values: Vec<(ColumnValue, f64)>,
}

Most-common-values list for a column.

Each entry is (value, frequency) where frequency is in [0, 1] — the fraction of total rows holding that exact value. Use for equality selectivity on skewed columns where one or two values dominate.

Fields

values: Vec<(ColumnValue, f64)>

Implementations

impl MostCommonValues

pub fn new(entries: Vec<(ColumnValue, f64)>) -> MostCommonValues

Construct from a (value, frequency) slice. Frequencies are expected to already be in [0, 1]; the constructor sorts by frequency descending so callers can .values[0] to get the hottest key.

pub fn frequency_of(&self, value: &ColumnValue) -> Option<f64>

Lookup value in the MCV list and return its frequency, or None if it isn’t tracked.

pub fn total_frequency(&self) -> f64

Sum of all tracked frequencies (always <= 1.0 if constructed from a valid sample).

pub fn len(&self) -> usize

Number of MCVs tracked.

pub fn is_empty(&self) -> bool

Whether the MCV list is empty.

Trait Implementations

impl Clone for MostCommonValues

fn clone(&self) -> MostCommonValues

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for MostCommonValues

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

Formats the value using the given formatter.

impl Default for MostCommonValues

fn default() -> MostCommonValues

Returns the “default value” for a type.