Struct IndexStats 

pub struct IndexStats {
    pub predicate_counts: RwLock<HashMap<String, usize>>,
    pub total_triples: AtomicUsize,
    pub subject_cardinality: RwLock<HashMap<String, usize>>,
    pub object_cardinality: RwLock<HashMap<String, usize>>,
    pub join_selectivity_cache: RwLock<HashMap<String, f64>>,
    /* private fields */
}

Extended index statistics for pattern optimization

Fields

predicate_counts: RwLock<HashMap<String, usize>>

Predicate occurrence counts

total_triples: AtomicUsize

Total number of triples

subject_cardinality: RwLock<HashMap<String, usize>>

Subject cardinality estimates

object_cardinality: RwLock<HashMap<String, usize>>

Object cardinality estimates

join_selectivity_cache: RwLock<HashMap<String, f64>>

Join selectivity cache

Implementations

impl IndexStats

pub fn new() -> Self

Create new index statistics

pub fn update_predicate_count(&self, predicate: &str, count: usize)

Update predicate count

pub fn set_total_triples(&self, count: usize)

Set total triples

pub fn update_subject_cardinality(&self, predicate: &str, cardinality: usize)

Update subject cardinality estimate

pub fn update_object_cardinality(&self, predicate: &str, cardinality: usize)

Update object cardinality estimate

pub fn cache_join_selectivity(&self, pattern_pair: &str, selectivity: f64)

Cache join selectivity

pub fn get_join_selectivity(&self, pattern_pair: &str) -> Option<f64>

Get cached join selectivity

Trait Implementations

impl Debug for IndexStats

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

Formats the value using the given formatter.

impl Default for IndexStats

fn default() -> IndexStats

Returns the “default value” for a type.