Trait SourceStatistics 

pub trait SourceStatistics {
    // Required method
    fn relation_statistics(&self, table: &str) -> Option<RelationStats>;

    // Provided methods
    fn source_access_estimate(
        &self,
        _source: &SourcePlan,
    ) -> Option<LocalAccessEstimate> { ... }
    fn local_access_estimate(
        &self,
        _table: &str,
        _predicate: &ScalarExpr,
    ) -> Option<LocalAccessEstimate> { ... }
}

Cardinality and column statistics used to cost base relations during join enumeration. Engines implement this against their live catalogue; callers without a catalogue still get deterministic DPccp enumeration from the optimizer’s fallback cardinality.

Required Methods

fn relation_statistics(&self, table: &str) -> Option<RelationStats>

Provided Methods

fn source_access_estimate( &self, _source: &SourcePlan, ) -> Option<LocalAccessEstimate>

Estimate a non-table source that can participate as one atom in an inner-join region. Returning None keeps that region in SQL order.

fn local_access_estimate( &self, _table: &str, _predicate: &ScalarExpr, ) -> Option<LocalAccessEstimate>

Estimate a predicate that references only table. Returning None delegates to the planner’s scalar selectivity model.

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors

impl<F> SourceStatistics for F

where F: Fn(&str) -> Option<RelationStats>,