numPartitions method that returns the value of spark.sql.shuffle.partitions for the number of partitions to use for joins and aggregations. It is later used in
BasicOperators strategy with
RepartitionByExpression logical operator.
strategies collection uses
extraStrategies extension point (defined as the argument to the constructor) and the predefined collection of
collectPlaceholders required method returns a collection of
PlanLater and the corresponding logical plans.
prunePlans required method does nothing, i.e. it returns what it gets directly.