Struct datafusion_common::FunctionalDependencies

pub struct FunctionalDependencies { /* private fields */ }

This object encapsulates all functional dependencies in a given relation.

Implementations

impl FunctionalDependencies

pub fn empty() -> Self

Creates an empty FunctionalDependencies object.

pub fn new(dependencies: Vec<FunctionalDependence>) -> Self

Creates a new FunctionalDependencies object from a vector of FunctionalDependence objects.

pub fn new_from_constraints( constraints: Option<&Constraints>, n_field: usize ) -> Self

Creates a new FunctionalDependencies object from the given constraints.

pub fn with_dependency(self, mode: Dependency) -> Self

pub fn extend(&mut self, other: FunctionalDependencies)

Merges the given functional dependencies with these.

pub fn add_offset(&mut self, offset: usize)

Adds the offset value to source_indices and target_indices for each functional dependency.

pub fn project_functional_dependencies( &self, proj_indices: &[usize], n_out: usize ) -> FunctionalDependencies

Updates source_indices and target_indices of each functional dependence using the index mapping given in proj_indices.

Assume that proj_indices is [2, 5, 8] and we have a functional dependence [5] (source_indices) -> [5, 8] (target_indices). In the updated schema, fields at indices [2, 5, 8] will transform to [0, 1, 2]. Therefore, the resulting functional dependence will be [1] -> [1, 2].

pub fn join( &self, other: &FunctionalDependencies, join_type: &JoinType, left_cols_len: usize ) -> FunctionalDependencies

This function joins this set of functional dependencies with the other according to the given join_type.

pub fn extend_target_indices(&mut self, n_out: usize)

This function ensures that functional dependencies involving uniquely occuring determinant keys cover their entire table in terms of dependent columns.

Trait Implementations

impl Clone for FunctionalDependencies

fn clone(&self) -> FunctionalDependencies

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for FunctionalDependencies

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

Formats the value using the given formatter.

impl PartialEq<FunctionalDependencies> for FunctionalDependencies

fn eq(&self, other: &FunctionalDependencies) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Eq for FunctionalDependencies

impl StructuralEq for FunctionalDependencies

impl StructuralPartialEq for FunctionalDependencies