Window Unary Logical Operator

Window is a unary logical operator that…FIXME

Window is created when:

When requested for output schema attributes, Window requests the child logical operator for them and adds the attributes of the window named expressions.

Note	`Window` logical operator is a subject of pruning unnecessary window expressions in ColumnPruning logical optimization and collapsing window operators in CollapseWindow logical optimization.

Note	`Window` logical operator is resolved to a WindowExec in BasicOperators execution planning strategy.

window(
  windowExpressions: Seq[NamedExpression],
  partitionSpec: Seq[Expression],
  orderSpec: Seq[SortOrder]): LogicalPlan

window operator in Catalyst DSL creates a Window logical operator, e.g. for testing or Spark SQL internals exploration.

// FIXME: DEMO

Window takes the following when created:

windowOutputSet: AttributeSet

windowOutputSet simply creates a AttributeSet with the attributes of the window named expressions.

Note	`windowOutputSet` is used when: `ColumnPruning` logical optimization is executed (on a Project operator with a `Window` as the child operator) `CollapseWindow` logical optimization is executed (on a `Window` operator with another `Window` operator as the child)

Window