Struct Histogram 

pub struct Histogram {
    pub buckets: Vec<Bucket>,
    pub total_count: u64,
}

Equi-depth histogram over a single column.

Buckets are non-overlapping and sorted by min. Each bucket holds roughly total_count / bucket_count rows. Range selectivity is computed by counting buckets fully inside the query interval and approximating the partial buckets at the edges.

Fields

buckets: Vec<Bucket>

total_count: u64

Implementations

impl Histogram

pub fn equi_depth_from_sample( values: Vec<ColumnValue>, bucket_count: usize, ) -> Histogram

Build an equi-depth histogram from an in-memory sample.

bucket_count is clamped between 1 and values.len(). The caller is responsible for sampling — passing the full table works but is expensive on large columns.

pub fn range_selectivity( &self, lo: Option<&ColumnValue>, hi: Option<&ColumnValue>, ) -> f64

Estimate the fraction of rows whose value falls in [lo, hi] (both bounds inclusive when present).

None for either bound means “open” — [lo..] for upper-open, [..hi] for lower-open, and None/None returns 1.0 (every row qualifies).

Returns a value clamped to [0.0, 1.0].

pub fn bucket_count(&self) -> usize

Number of buckets in the histogram.

Trait Implementations

impl Clone for Histogram

fn clone(&self) -> Histogram

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Histogram

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

Formats the value using the given formatter.