I'm learning the code of Spark SQL.
I'm confused about how SchemaRDD executes each operator.
I'm tracing the code. I found toRDD() function in QueryExecution is the start for running a query. toRDD function will run SparkPlan, which is a tree structure.
However, I didn't find any iterative sentence in execute function for any detail operators. It seems Spark SQL will only run the top node in this tree.
I know the conclusion is wrong.But which code have I missed?