Struct JoinGraphStats 

pub struct JoinGraphStats {
    pub triple_count: u64,
    pub distinct_subjects: u64,
    pub distinct_predicates: u64,
    pub distinct_objects: u64,
    pub per_predicate_counts: HashMap<String, u64>,
}

Graph statistics used by the join-order optimizer for cardinality estimation.

Intentionally named JoinGraphStats to avoid collision with analytics::GraphStats.

Fields

triple_count: u64

Total number of triples in the graph.

distinct_subjects: u64

Number of distinct subjects.

distinct_predicates: u64

Number of distinct predicates.

distinct_objects: u64

Number of distinct objects.

per_predicate_counts: HashMap<String, u64>

Per-predicate triple counts (predicate URI → count).

Implementations

impl JoinGraphStats

pub fn new(triple_count: u64) -> Self

Create a new stats object with the given triple count.

pub fn with_details( triple_count: u64, distinct_subjects: u64, distinct_predicates: u64, distinct_objects: u64, per_predicate_counts: HashMap<String, u64>, ) -> Self

Create fully specified stats.

pub fn add_predicate_count(&mut self, predicate: impl Into<String>, count: u64)

Insert a predicate count entry.

pub fn predicate_selectivity(&self, predicate_uri: &str) -> f64

Estimated selectivity of a given predicate (fraction of triples with this predicate).

Trait Implementations

impl Clone for JoinGraphStats

fn clone(&self) -> JoinGraphStats

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for JoinGraphStats

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

Formats the value using the given formatter.

impl Default for JoinGraphStats

fn default() -> JoinGraphStats

Returns the “default value” for a type.