Type Definition datafusion::physical_expr::OrderingEquivalenceProperties

pub type OrderingEquivalenceProperties = EquivalenceProperties<Vec<PhysicalSortExpr, Global>>;

OrderingEquivalenceProperties keeps track of columns that describe the global ordering of the schema. These columns are not necessarily same; e.g.

┌-------┐
| a | b |
|---|---|
| 1 | 9 |
| 2 | 8 |
| 3 | 7 |
| 5 | 5 |
└---┴---┘

where both a ASC and b DESC can describe the table ordering. With OrderingEquivalenceProperties, we can keep track of these equivalences and treat a ASC and b DESC as the same ordering requirement.