gatorsmile commented on a change in pull request #23531: [SPARK-24497][SQL]
Support recursive SQL query
URL: https://github.com/apache/spark/pull/23531#discussion_r265348806
##########
File path:
sql/core/src/main/scala/org/apache/spark/sql/execution/basicPhysicalOperators.scala
##########
@@ -228,6 +233,97 @@ case class FilterExec(condition: Expression, child:
SparkPlan)
override def outputPartitioning: Partitioning = child.outputPartitioning
}
+/** Physical plan for RecursiveTable. */
+case class RecursiveTableExec(
+ name: String,
+ anchorTerms: Seq[SparkPlan],
+ recursiveTerms: Seq[SparkPlan],
+ limit: Option[Long]) extends SparkPlan with LoopStart {
+ override def children: Seq[SparkPlan] = anchorTerms ++ recursiveTerms
+
+ override def output: Seq[Attribute] =
anchorTerms.head.output.map(_.withNullability(true))
+
+ override val doNotPrepareInAdvance: Seq[SparkPlan] = recursiveTerms
+
+ override protected def doExecute(): RDD[InternalRow] = {
+ val prevIterationRDDs = ArrayBuffer.empty[RDD[InternalRow]]
+ var prevIterationCount = 0L
+ val anchorTermsIterator = anchorTerms.iterator
+ while (anchorTermsIterator.hasNext && limit.forall(_ >
prevIterationCount)) {
+ val anchorTerm = anchorTermsIterator.next()
+
+ val rdd = anchorTerm.execute().map(_.copy()).cache()
+ val count = rdd.count()
+ if (count > 0) {
+ prevIterationRDDs += rdd
+ prevIterationCount += count
+ }
+ }
+
+ val allRDDs = ArrayBuffer(prevIterationRDDs: _*)
+ var allCount = prevIterationCount
+ var level = 0
+ val levelLimit = conf.recursionLevelLimit
+ while (prevIterationCount > 0 && limit.forall(_ > allCount)) {
+ if (level > levelLimit) {
+ throw new SparkException(s"Recursion level limit ${levelLimit} reached
but query has not " +
+ s"exhausted, try increasing ${SQLConf.RECURSION_LEVEL_LIMIT.key}")
+ }
+
+ val prevIterationResult = sparkContext.union(prevIterationRDDs)
+
+ prevIterationRDDs.clear()
+ prevIterationCount = 0
+ val recursiveTermsIterator = recursiveTerms.iterator
+ while (recursiveTermsIterator.hasNext && limit.forall(_ > allCount +
prevIterationCount)) {
+ val recursiveTerm = recursiveTermsIterator.next()
+
+ val newCoordinators = mutable.Map.empty[ExchangeCoordinator,
Some[ExchangeCoordinator]]
+ val newRecursiveTerm = recursiveTerm.transform {
Review comment:
The current approach of this PR is very intrusive. I think @maryannxue
suggestions make sense.
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