spark InlineCTE 源码
spark InlineCTE 代码
文件路径:/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/InlineCTE.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.catalyst.optimizer
import scala.collection.mutable
import org.apache.spark.sql.catalyst.analysis.DeduplicateRelations
import org.apache.spark.sql.catalyst.expressions.{Alias, OuterReference, SubqueryExpression}
import org.apache.spark.sql.catalyst.plans.Inner
import org.apache.spark.sql.catalyst.plans.logical.{CTERelationDef, CTERelationRef, Join, JoinHint, LogicalPlan, Project, Subquery, WithCTE}
import org.apache.spark.sql.catalyst.rules.Rule
import org.apache.spark.sql.catalyst.trees.TreePattern.{CTE, PLAN_EXPRESSION}
/**
* Inlines CTE definitions into corresponding references if either of the conditions satisfies:
* 1. The CTE definition does not contain any non-deterministic expressions or contains attribute
* references to an outer query. If this CTE definition references another CTE definition that
* has non-deterministic expressions, it is still OK to inline the current CTE definition.
* 2. The CTE definition is only referenced once throughout the main query and all the subqueries.
*
* CTE definitions that appear in subqueries and are not inlined will be pulled up to the main
* query level.
*
* @param alwaysInline if true, inline all CTEs in the query plan.
*/
case class InlineCTE(alwaysInline: Boolean = false) extends Rule[LogicalPlan] {
override def apply(plan: LogicalPlan): LogicalPlan = {
if (!plan.isInstanceOf[Subquery] && plan.containsPattern(CTE)) {
val cteMap = mutable.HashMap.empty[Long, (CTERelationDef, Int)]
buildCTEMap(plan, cteMap)
val notInlined = mutable.ArrayBuffer.empty[CTERelationDef]
val inlined = inlineCTE(plan, cteMap, notInlined)
// CTEs in SQL Commands have been inlined by `CTESubstitution` already, so it is safe to add
// WithCTE as top node here.
if (notInlined.isEmpty) {
inlined
} else {
WithCTE(inlined, notInlined.toSeq)
}
} else {
plan
}
}
private def shouldInline(cteDef: CTERelationDef, refCount: Int): Boolean = alwaysInline || {
// We do not need to check enclosed `CTERelationRef`s for `deterministic` or `OuterReference`,
// because:
// 1) It is fine to inline a CTE if it references another CTE that is non-deterministic;
// 2) Any `CTERelationRef` that contains `OuterReference` would have been inlined first.
refCount == 1 ||
cteDef.deterministic ||
cteDef.child.exists(_.expressions.exists(_.isInstanceOf[OuterReference]))
}
def buildCTEMap(
plan: LogicalPlan,
cteMap: mutable.HashMap[Long, (CTERelationDef, Int)]): Unit = {
plan match {
case WithCTE(_, cteDefs) =>
cteDefs.foreach { cteDef =>
cteMap.put(cteDef.id, (cteDef, 0))
}
case ref: CTERelationRef =>
val (cteDef, refCount) = cteMap(ref.cteId)
cteMap.update(ref.cteId, (cteDef, refCount + 1))
case _ =>
}
if (plan.containsPattern(CTE)) {
plan.children.foreach { child =>
buildCTEMap(child, cteMap)
}
plan.expressions.foreach { expr =>
if (expr.containsAllPatterns(PLAN_EXPRESSION, CTE)) {
expr.foreach {
case e: SubqueryExpression =>
buildCTEMap(e.plan, cteMap)
case _ =>
}
}
}
}
}
private def inlineCTE(
plan: LogicalPlan,
cteMap: mutable.HashMap[Long, (CTERelationDef, Int)],
notInlined: mutable.ArrayBuffer[CTERelationDef]): LogicalPlan = {
plan match {
case WithCTE(child, cteDefs) =>
cteDefs.foreach { cteDef =>
val (cte, refCount) = cteMap(cteDef.id)
if (refCount > 0) {
val inlined = cte.copy(child = inlineCTE(cte.child, cteMap, notInlined))
cteMap.update(cteDef.id, (inlined, refCount))
if (!shouldInline(inlined, refCount)) {
notInlined.append(inlined)
}
}
}
inlineCTE(child, cteMap, notInlined)
case ref: CTERelationRef =>
val (cteDef, refCount) = cteMap(ref.cteId)
if (shouldInline(cteDef, refCount)) {
if (ref.outputSet == cteDef.outputSet) {
cteDef.child
} else {
val ctePlan = DeduplicateRelations(
Join(cteDef.child, cteDef.child, Inner, None, JoinHint(None, None))).children(1)
val projectList = ref.output.zip(ctePlan.output).map { case (tgtAttr, srcAttr) =>
if (srcAttr.semanticEquals(tgtAttr)) {
tgtAttr
} else {
Alias(srcAttr, tgtAttr.name)(exprId = tgtAttr.exprId)
}
}
Project(projectList, ctePlan)
}
} else {
ref
}
case _ if plan.containsPattern(CTE) =>
plan
.withNewChildren(plan.children.map(child => inlineCTE(child, cteMap, notInlined)))
.transformExpressionsWithPruning(_.containsAllPatterns(PLAN_EXPRESSION, CTE)) {
case e: SubqueryExpression =>
e.withNewPlan(inlineCTE(e.plan, cteMap, notInlined))
}
case _ => plan
}
}
}
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