Type Definition datafusion_physical_expr::equivalence::OrderingEquivalenceProperties
source · pub type OrderingEquivalenceProperties = EquivalenceProperties<LexOrdering>;
Expand description
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.