Struct SampleMetadata 

pub struct SampleMetadata {
    pub total_rows: usize,
    pub sample_size: usize,
    pub sampling_ratio: f64,
    pub sampled: bool,
    pub confidence_level: f64,
}

Metadata about a sample

Fields

total_rows: usize

Total number of rows in the table

sample_size: usize

Number of rows in the sample

sampling_ratio: f64

Sampling ratio (sample_size / total_rows)

sampled: bool

Whether sampling was actually used

confidence_level: f64

Confidence level for statistical estimates

Implementations

impl SampleMetadata

pub fn new( total_rows: usize, sample_size: usize, sampled: bool, confidence_level: f64, ) -> Self

Create metadata for a sample

pub fn extrapolate_count(&self, sample_count: usize) -> usize

Extrapolate a count from sample to full table

Given a count in the sample, estimate the count in the full table

pub fn extrapolate_frequency(&self, sample_frequency: f64) -> f64

Extrapolate a frequency/selectivity from sample to full table

Frequencies typically don’t need adjustment, but we apply a small confidence adjustment for small samples

pub fn standard_error(&self, proportion: f64) -> f64

Estimate the standard error for a proportion

Used to provide confidence intervals for selectivity estimates

pub fn confidence_interval(&self, proportion: f64) -> (f64, f64)

Get confidence interval for a proportion estimate

Returns (lower_bound, upper_bound) for the confidence level

Trait Implementations

impl Clone for SampleMetadata

fn clone(&self) -> SampleMetadata

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for SampleMetadata

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

Formats the value using the given formatter.