Struct CardinalityFeedback 

pub struct CardinalityFeedback {
    pub predicate_hash: u64,
    pub table_name: String,
    pub column_name: Option<String>,
    pub estimated_rows: u64,
    pub actual_rows: u64,
    pub correction_factor: f64,
    pub sample_count: u64,
    pub last_updated: i64,
}

Cardinality feedback entry for a predicate pattern

Fields

predicate_hash: u64

Hash of the predicate structure (not values)

table_name: String

Table name this feedback applies to

column_name: Option<String>

Column name (if applicable)

estimated_rows: u64

Estimated row count from cost model

actual_rows: u64

Actual row count from execution

correction_factor: f64

Correction factor (actual/estimated), smoothed over samples

sample_count: u64

Number of samples used to compute the correction

last_updated: i64

Last update timestamp (nanoseconds since epoch)

Implementations

impl CardinalityFeedback

pub fn new( predicate_hash: u64, table_name: impl Into<String>, column_name: Option<String>, estimated_rows: u64, actual_rows: u64, ) -> Self

Create a new feedback entry from estimated and actual row counts

pub fn update( &mut self, estimated_rows: u64, actual_rows: u64, decay_factor: f64, )

Update feedback with a new sample using exponential moving average

pub fn is_reliable(&self) -> bool

Check if this feedback has enough samples to be reliable

pub fn apply_correction(&self, base_estimate: u64) -> u64

Apply correction to an estimate

Trait Implementations

impl Clone for CardinalityFeedback

fn clone(&self) -> CardinalityFeedback

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for CardinalityFeedback

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

Formats the value using the given formatter.