Struct OrderingEquivalenceCache 

struct OrderingEquivalenceCache {
    normal_cls: OrderingEquivalenceClass,
    leading_map: HashMap<Arc<dyn PhysicalExpr>, Vec<usize>>,
}

This object serves as a cache for storing equivalent sort expressions in normal form, and a map associating leading sort expressions with full lexicographical orderings. With this information, DataFusion can efficiently determine whether a given ordering is satisfied by the existing orderings, and discover new orderings based on the existing equivalence properties.

Fields

normal_cls: OrderingEquivalenceClass

Equivalent sort expressions in normal form.

leading_map: HashMap<Arc<dyn PhysicalExpr>, Vec<usize>>

Map associating leading sort expressions with full lexicographical orderings. Values are indices into normal_cls.

Implementations

impl OrderingEquivalenceCache

pub fn new( orderings: impl IntoIterator<Item = impl IntoIterator<Item = PhysicalSortExpr>>, ) -> Self

Creates a new OrderingEquivalenceCache object with the given equivalent orderings, which should be in normal form.

pub fn update_map(&mut self)

Updates/reconstructs the leading expression map according to the normal ordering equivalence class within.

pub fn clear(&mut self)

Clears the cache, removing all orderings and leading expressions.

Trait Implementations

impl Clone for OrderingEquivalenceCache

fn clone(&self) -> OrderingEquivalenceCache

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for OrderingEquivalenceCache

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

Formats the value using the given formatter.

impl Default for OrderingEquivalenceCache

fn default() -> OrderingEquivalenceCache

Returns the “default value” for a type.