Module datafusion_physical_expr::equivalence

Structs

• EquivalenceProperties
  Represents a collection of EquivalentClass (equivalences between columns in relations)
• EquivalentClass
  EquivalentClass is a set of Columns or OrderedColumns that are known to have the same value in all tuples in a relation. EquivalentClass<Column> is generated by equality predicates, typically equijoin conditions and equality conditions in filters. EquivalentClass<OrderedColumn> is generated by the ROW_NUMBER window function.
• OrderedColumn
  This object represents a Column with a definite ordering, for example A ASC and is used to represent equivalent orderings in the optimizer.
• OrderingEquivalenceBuilder
  This is a builder object facilitating incremental construction for ordering equivalences.

Functions

• project_equivalence_properties
  This function applies the given projection to the given equivalence properties to compute the resulting (projected) equivalence properties; e.g.
• project_ordering_equivalence_properties
  This function applies the given projection to the given ordering equivalence properties to compute the resulting (projected) ordering equivalence properties; e.g.

Type Definitions

• OrderingEquivalenceProperties
  OrderingEquivalenceProperties keeps track of columns that describe the global ordering of the schema. These columns are not necessarily same; e.g.
• OrderingEquivalentClass
  Vec<OrderedColumn> stores the lexicographical ordering for a schema. OrderingEquivalentClass keeps track of different alternative orderings than can describe the schema. For instance, for the table below |a|b|c|d| |1|4|3|1| |2|3|3|2| |3|1|2|2| |3|2|1|3| both vec![a ASC, b ASC] and vec![c DESC, d ASC] describe the ordering of the table. For this case, we say that vec![a ASC, b ASC], and vec![c DESC, d ASC] are ordering equivalent.