org.apache.spark.sql.execution

Interface Command

All Known Implementing Classes:

CacheCommand, DescribeCommand, DescribeHiveTableCommand, ExplainCommand, NativeCommand, SetCommand

public interface Command

Method Summary

Methods

Modifier and Type	Method and Description
scala.collection.Seq<Object>	sideEffectResult() A concrete command should override this lazy field to wrap up any side effects caused by the command or any other computation that should be evaluated exactly once.

Method Detail

sideEffectResult

scala.collection.Seq<Object> sideEffectResult()

A concrete command should override this lazy field to wrap up any side effects caused by the command or any other computation that should be evaluated exactly once. The value of this field can be used as the contents of the corresponding RDD generated from the physical plan of this command.

The execute() method of all the physical command classes should reference sideEffectResult so that the command can be executed eagerly right after the command query is created.