Struct CostModel 

pub struct CostModel { /* private fields */ }

Cost model for query operations.

Implementations

impl CostModel

pub fn new() -> Self

Create a new cost model.

pub fn register_statistics(&self, table: String, stats: Statistics)

Register statistics for a table.

pub fn get_statistics(&self, table: &str) -> Option<Statistics>

Get statistics for a table.

pub fn scan_cost(&self, table: &str) -> Cost

Estimate cost of a table scan.

pub fn filter_cost(&self, input_rows: usize, selectivity: f64) -> Cost

Estimate cost of a filter operation.

pub fn join_cost( &self, left_rows: usize, right_rows: usize, join_type: JoinType, ) -> Cost

Estimate cost of a join operation.

pub fn aggregate_cost(&self, input_rows: usize, group_count: usize) -> Cost

Estimate cost of aggregation.

pub fn sort_cost(&self, input_rows: usize) -> Cost

Estimate cost of sorting.

pub fn estimate_selectivity(&self, table: &str, expr: &Expr) -> f64

Estimate selectivity of a predicate.

Trait Implementations

impl Default for CostModel

fn default() -> Self

Returns the “default value” for a type.