spark DatasetHolder 源码
spark DatasetHolder 代码
文件路径：/sql/core/src/main/scala/org/apache/spark/sql/DatasetHolder.scala
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.spark.sql
import org.apache.spark.annotation.Stable
/**
* A container for a [[Dataset]], used for implicit conversions in Scala.
*
* To use this, import implicit conversions in SQL:
* {{{
* val spark: SparkSession = ...
* import spark.implicits._
* }}}
*
* @since 1.6.0
*/
@Stable
case class DatasetHolder[T] private[sql](private val ds: Dataset[T]) {
// This is declared with parentheses to prevent the Scala compiler from treating
// `rdd.toDS("1")` as invoking this toDS and then apply on the returned Dataset.
def toDS(): Dataset[T] = ds
// This is declared with parentheses to prevent the Scala compiler from treating
// `rdd.toDF("1")` as invoking this toDF and then apply on the returned DataFrame.
def toDF(): DataFrame = ds.toDF()
def toDF(colNames: String*): DataFrame = ds.toDF(colNames : _*)
}
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