Enum SamplingStrategy 

pub enum SamplingStrategy {
    None,
    Random {
        size: usize,
    },
    Reservoir {
        size: usize,
    },
    Systematic {
        interval: usize,
    },
}

How rows are selected for profiling.

Strategies divide into two families, which differ in cost. Systematic decides each row as it arrives and adds no memory. Random and Reservoir cannot know the final sample until the source ends, so they hold size rows in memory and the profile is computed from that buffer.

Every strategy is applied by RowSampler.

Variants

None

No sampling - analyze all data

Random

A uniform random sample of exactly size rows (or every row, when the source is shorter).

Over a source of unknown length this is reservoir sampling, so it holds size rows in memory and is equivalent to Reservoir; both names are kept because both are familiar.

Fields

size: usize

Reservoir

A uniform random sample of exactly size rows, selected with Algorithm R over a single pass.

Holds size rows in memory: membership is not final until the source ends, and statistics folded in earlier could not be retracted.

Fields

size: usize

Systematic

Every interval-th row, starting at the first.

Fields

interval: usize

Implementations

impl SamplingStrategy

pub fn description(&self) -> String

Get description of the sampling strategy

Trait Implementations

impl Clone for SamplingStrategy

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for SamplingStrategy

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

Formats the value using the given formatter.