How does Spark SQL traverse the physical tree?

Hi All, 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

Re: How does Spark SQL traverse the physical tree?

You are pretty close. The QueryExecution is what drives the phases from parsing to execution. Once we have a final SparkPlan (the physical plan), toRdd just calls execute() which recursively calls execute() on children until we hit a leaf operator. This gives us an RDD[Row] that will compute