Struct CostModel 

pub struct CostModel { /* private fields */ }

Query cost model that estimates relative execution cost of a LogicalPlan.

Missing tables fall back to TableStats::default.

Implementations

impl CostModel

pub fn new() -> Self

Create a new CostModel with default weights and no table statistics.

pub fn with_table_stats(self, table: &str, stats: TableStats) -> Self

Register per-table statistics for a specific table.

Table names are compared case-insensitively.

pub fn with_cpu_weight(self, w: f64) -> Self

Override the CPU-cost weight used to compute total_cost.

pub fn with_filter_selectivity(self, s: f64) -> Self

Override the per-predicate filter selectivity (fraction of rows passing).

pub fn estimate(&self, plan: &LogicalPlan) -> CostEstimate

Estimate the cost of executing plan.

impl CostModel

pub fn explain_costs(&self, plan: &LogicalPlan) -> NodeCost

Build a NodeCost tree for plan by recursively estimating each node.

Trait Implementations

impl Default for CostModel

fn default() -> Self

Returns the “default value” for a type.