Struct CostEstimator 

pub struct CostEstimator { /* private fields */ }

Cost estimator for query plans

Implementations

impl CostEstimator

pub fn new() -> CostEstimator

Create a new cost estimator with default parameters and a NullProvider — no real stats, pure heuristic mode.

pub fn with_stats(provider: Arc<dyn StatsProvider>) -> CostEstimator

Create a cost estimator that consults provider for real table / column / index statistics. Any lookups the provider cannot satisfy fall back to the heuristic path automatically.

pub fn set_stats(&mut self, provider: Arc<dyn StatsProvider>)

Swap the stats provider on an existing estimator. Useful for tests and for planners that build one CostEstimator and repoint it at per-query snapshots.

pub fn estimate(&self, query: &QueryExpr) -> PlanCost

Estimate cost of a query expression

pub fn estimate_cardinality(&self, query: &QueryExpr) -> CardinalityEstimate

Estimate cardinality of a query result

Trait Implementations

impl Default for CostEstimator

fn default() -> CostEstimator

Returns the “default value” for a type.