摘要:
def show(numRows: Int): Unit = show(numRows, truncate = true) /** * Displays the top 20 rows of Dataset in a tabular form. Strings more than 20 charac 阅读全文
摘要:
def sample( withReplacement: Boolean, fraction: Double, seed: Long = Utils.random.nextLong): RDD[T] = { require(fraction >= 0, s"Fraction must be nonn 阅读全文
摘要:
DataFrame注册成一张表格,如果通过CreateTempView这种方式来创建,那么该表格Session有效,如果通过CreateGlobalTempView来创建,那么该表格跨Session有效,但是SQL语句访问该表格的时候需要加上前缀global_temp dataframe 转换为临时 阅读全文