Spark临时表tempView的注册/使用/注销/注意事项(推荐)

sql("select a,b from table where xxx").createTempView("view1")
sql("select a from view1 where xxx").show()
sql("select b from view1 where xxx").show()

// 创建它的SparkSession对象终止前有效
df.createOrReplaceTempView("tempViewName")  
// spark应用程序终止前有效
df.createOrReplaceGlobalTempView("tempViewName") 

spark.catalog.dropTempView("tempViewName")
spark.catalog.dropGlobalTempView("tempViewName")

session.table("tempViewName").cache()

session.table("tempViewName").unpersist()

commonDF.cahe() 或 commonDF.persist(StorageLevel.MEMORY_AND_DISK)
commonDF.createOrReplaceTempView("tempViewName")

commonDF.unpersist()

  
  def createOrReplaceTempView(viewName: String): Unit = withPlan {
    createTempViewCommand(viewName, replace = true, global = false)
  }

  @throws[AnalysisException]
  def createGlobalTempView(viewName: String): Unit = withPlan {
    createTempViewCommand(viewName, replace = false, global = true)
  }