Struct ColumnStatistics 

pub struct ColumnStatistics {
    pub distinct_count: u64,
    pub total_count: u64,
    pub null_count: u64,
    pub min_value: Option<Value>,
    pub max_value: Option<Value>,
    pub avg_value: Option<f64>,
    pub histogram: Option<Histogram>,
    pub most_common: Vec<(Value, f64)>,
}

Statistics for a column/property.

Fields

distinct_count: u64

Number of distinct values.

total_count: u64

Total number of values (including nulls).

null_count: u64

Number of null values.

min_value: Option<Value>

Minimum value (if applicable).

max_value: Option<Value>

Maximum value (if applicable).

avg_value: Option<f64>

Average value (for numeric types).

histogram: Option<Histogram>

Equi-depth histogram (for selectivity estimation).

most_common: Vec<(Value, f64)>

Most common values with their frequencies.

Implementations

impl ColumnStatistics

pub fn new(distinct_count: u64, total_count: u64, null_count: u64) -> Self

Creates new column statistics with basic info.

pub fn with_min_max(self, min: Value, max: Value) -> Self

Sets min/max values.

pub fn with_avg(self, avg: f64) -> Self

Sets the average value.

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

Sets the histogram.

pub fn with_most_common(self, values: Vec<(Value, f64)>) -> Self

Sets the most common values.

pub fn null_fraction(&self) -> f64

Returns the null fraction.

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

Estimates selectivity for an equality predicate.

pub fn estimate_range_selectivity( &self, lower: Option<&Value>, upper: Option<&Value>, ) -> f64

Estimates selectivity for a range predicate.

Trait Implementations

impl Clone for ColumnStatistics

fn clone(&self) -> ColumnStatistics

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ColumnStatistics

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

Formats the value using the given formatter.