Module functional_dependencies 

FunctionalDependencies keeps track of functional dependencies inside DFSchema.

Structs

Constraints

This object encapsulates a list of functional constraints:

FunctionalDependence

This object defines a functional dependence in the schema. A functional dependence defines a relationship between determinant keys and dependent columns. A determinant key is a column, or a set of columns, whose value uniquely determines values of some other (dependent) columns. If two rows have the same determinant key, dependent columns in these rows are necessarily the same. If the determinant key is unique, the set of dependent columns is equal to the entire schema and the determinant key can serve as a primary key. Note that a primary key may “downgrade” into a determinant key due to an operation such as a join, and this object is used to track dependence relationships in such cases. For more information on functional dependencies, see: https://www.scaler.com/topics/dbms/functional-dependency-in-dbms/

FunctionalDependencies

This object encapsulates all functional dependencies in a given relation.

Enums

Constraint

This object defines a constraint on a table.

Dependency

Describes functional dependency mode.

Functions

add_offset_to_vec 🔒

Adds offset value to each entry inside in_data.

aggregate_functional_dependencies

Calculates functional dependencies for aggregate output, when there is a GROUP BY expression.

get_required_group_by_exprs_indices

Returns indices for the minimal subset of GROUP BY expressions that are functionally equivalent to the original set of GROUP BY expressions.

get_target_functional_dependencies

Returns target indices, for the determinant keys that are inside group by expressions.

update_elements_with_matching_indices 🔒

Updates entries inside the entries vector with their corresponding indices inside the proj_indices vector.