WeichenXu123 commented on a change in pull request #25512: [SPARK-28782][SQL]
Generator support in aggregate expressions
URL: https://github.com/apache/spark/pull/25512#discussion_r319955689
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File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala
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@@ -2018,6 +2018,62 @@ class Analyzer(
throw new AnalysisException("Only one generator allowed per select
clause but found " +
generators.size + ": " + generators.map(toPrettySQL).mkString(", "))
+ case Aggregate(_, aggList, _) if aggList.exists(hasNestedGenerator) =>
+ val nestedGenerator = aggList.find(hasNestedGenerator).get
+ throw new AnalysisException("Generators are not supported when it's
nested in " +
+ "expressions, but got: " + toPrettySQL(trimAlias(nestedGenerator)))
+
+ case Aggregate(_, aggList, _) if aggList.count(hasGenerator) > 1 =>
+ val generators = aggList.filter(hasGenerator).map(trimAlias)
+ throw new AnalysisException("Only one generator allowed per aggregate
clause but found " +
+ generators.size + ": " + generators.map(toPrettySQL).mkString(", "))
+
+ case agg @ Aggregate(groupList, aggList, child) if aggList.forall {
+ case AliasedGenerator(generator, _, _) => generator.childrenResolved
+ case other => other.resolved
+ } =>
+ // Holds the resolved generator, if one exists in the project list.
+ var generatorVisited = false
+
+ val projectExprs = Array.ofDim[NamedExpression](aggList.length)
+ val newAggList = aggList
+
.map(CleanupAliases.trimNonTopLevelAliases(_).asInstanceOf[NamedExpression])
+ .zipWithIndex
+ .flatMap {
+ case (AliasedGenerator(generator, names, outer), idx) =>
+ // It's a sanity check, this should not happen as the previous
case will throw
+ // exception earlier.
+ assert(!generatorVisited, "More than one generator found in
aggregate.")
+ generatorVisited = true
+
+ val newGenChildren: Seq[Expression] =
generator.children.zipWithIndex.map {
+ case (e, idx) => if (e.foldable) e else Alias(e,
s"_gen_input_${idx}")()
+ }
+ val newGenerator = {
+ val g = generator.withNewChildren(newGenChildren.map { e =>
+ if (e.foldable) e else e.asInstanceOf[Alias].toAttribute
+ }).asInstanceOf[Generator]
+ if (outer) GeneratorOuter(g) else g
+ }
+ val newAliasedGenerator = if (names.length == 1) {
+ Alias(newGenerator, names(0))()
+ } else {
+ MultiAlias(newGenerator, names)
+ }
+ projectExprs(idx) = newAliasedGenerator
+
newGenChildren.filter(!_.foldable).asInstanceOf[Seq[NamedExpression]]
+ case (other, idx) =>
+ projectExprs(idx) = other.toAttribute
+ other :: Nil
+ }
+
+ if (generatorVisited) {
+ val newAgg = Aggregate(groupList, newAggList, child)
+ Project(projectExprs.toList, newAgg)
+ } else {
+ agg
+ }
+
case p @ Project(projectList, child) =>
Review comment:
I prefer current switch case order.
The first four switch case only do some check so put them in front.
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