Struct ColumnStats 

pub struct ColumnStats {
    pub ndv: usize,
    pub null_count: usize,
    pub min_value: Option<ColumnValue>,
    pub max_value: Option<ColumnValue>,
    pub histogram: Option<Histogram>,
    pub mcv: Vec<(ColumnValue, usize)>,
}

Column-level statistics

Fields

ndv: usize

Number of distinct values

null_count: usize

Number of null values

min_value: Option<ColumnValue>

Minimum value (for ordered types)

max_value: Option<ColumnValue>

Maximum value (for ordered types)

histogram: Option<Histogram>

Histogram for distribution

mcv: Vec<(ColumnValue, usize)>

Most common values and their frequencies

Implementations

impl ColumnStats

pub fn new(ndv: usize, null_count: usize) -> Self

Create new column statistics

pub fn with_range(self, min: ColumnValue, max: ColumnValue) -> Self

Set min/max values

pub fn with_histogram(self, histogram: Histogram) -> Self

Set histogram

pub fn with_mcv(self, mcv: Vec<(ColumnValue, usize)>) -> Self

Set most common values

pub fn estimate_equality_selectivity(&self, value: &ColumnValue) -> f64

Estimate selectivity for equality predicate

pub fn estimate_range_selectivity( &self, start: &ColumnValue, end: &ColumnValue, ) -> f64

Estimate selectivity for range predicate

Trait Implementations

impl Clone for ColumnStats

fn clone(&self) -> ColumnStats

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ColumnStats

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

Formats the value using the given formatter.