It's weird to me that the simple show function will cost 2 spark jobs. DataFrame#explain shows it is a very simple operation, not sure why need 2 jobs.
== Parsed Logical Plan == Relation[age#0L,name#1] JSONRelation[file:/Users/hadoop/github/spark/examples/src/main/resources/people.json] == Analyzed Logical Plan == age: bigint, name: string Relation[age#0L,name#1] JSONRelation[file:/Users/hadoop/github/spark/examples/src/main/resources/people.json] == Optimized Logical Plan == Relation[age#0L,name#1] JSONRelation[file:/Users/hadoop/github/spark/examples/src/main/resources/people.json] == Physical Plan == Scan JSONRelation[file:/Users/hadoop/github/spark/examples/src/main/resources/people.json][age#0L,name#1] -- Best Regards Jeff Zhang
