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/*
* 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.execution
import org.apache.spark.sql.catalyst.{expressions, InternalRow}
import org.apache.spark.sql.catalyst.expressions.{ExprId, Literal, SubqueryExpression}
import org.apache.spark.sql.catalyst.expressions.codegen.{CodegenContext, ExprCode}
import org.apache.spark.sql.catalyst.plans.logical.{LogicalPlan, ReturnAnswer}
import org.apache.spark.sql.catalyst.rules.Rule
import org.apache.spark.sql.internal.SessionState
import org.apache.spark.sql.types.DataType
/**
* A subquery that will return only one row and one column.
*
* This is the physical copy of ScalarSubquery to be used inside SparkPlan.
*/
case class ScalarSubquery(
@transient executedPlan: SparkPlan,
exprId: ExprId)
extends SubqueryExpression {
override def query: LogicalPlan = throw new UnsupportedOperationException
override def withNewPlan(plan: LogicalPlan): SubqueryExpression = {
throw new UnsupportedOperationException
}
override def plan: SparkPlan = Subquery(simpleString, executedPlan)
override def dataType: DataType = executedPlan.schema.fields.head.dataType
override def nullable: Boolean = true
override def toString: String = s"subquery#${exprId.id}"
// the first column in first row from `query`.
private var result: Any = null
def updateResult(v: Any): Unit = {
result = v
}
override def eval(input: InternalRow): Any = result
override def genCode(ctx: CodegenContext, ev: ExprCode): String = {
Literal.create(result, dataType).genCode(ctx, ev)
}
}
/**
* Convert the subquery from logical plan into executed plan.
*/
case class PlanSubqueries(sessionState: SessionState) extends Rule[SparkPlan] {
def apply(plan: SparkPlan): SparkPlan = {
plan.transformAllExpressions {
case subquery: expressions.ScalarSubquery =>
val sparkPlan = sessionState.planner.plan(ReturnAnswer(subquery.query)).next()
val executedPlan = sessionState.prepareForExecution.execute(sparkPlan)
ScalarSubquery(executedPlan, subquery.exprId)
}
}
}
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