A trait that should be mixed into query operators where an single instance might appear multiple
times in a logical query plan. It is invalid to have multiple copies of the same attribute
produced by distinct operators in a query tree as this breaks the guarantee that expression
ids, which are used to differentiate attributes, are unique.
During analysis, operators that include this trait may be asked to produce a new version
of itself with globally unique expression ids.
A trait that should be mixed into query operators where an single instance might appear multiple times in a logical query plan. It is invalid to have multiple copies of the same attribute produced by distinct operators in a query tree as this breaks the guarantee that expression ids, which are used to differentiate attributes, are unique.
During analysis, operators that include this trait may be asked to produce a new version of itself with globally unique expression ids.