beliefer commented on a change in pull request #27058: [SPARK-30395][SQL] When
one or more DISTINCT aggregate expressions operate on the same field, the
DISTINCT aggregate expression allows the use of the FILTER clause
URL: https://github.com/apache/spark/pull/27058#discussion_r364580011
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/RewriteDistinctAggregates.scala
##########
@@ -317,7 +363,74 @@ object RewriteDistinctAggregates extends
Rule[LogicalPlan] {
}
Aggregate(groupByAttrs, patchedAggExpressions, firstAggregate)
} else {
- a
+ val (distinctAggExpressions, regularAggExpressions) =
aggExpressions.partition(_.isDistinct)
+ if (distinctAggExpressions.exists(_.filter.isDefined)) {
+ val regularAggExprs = regularAggExpressions.filter(e =>
e.children.exists(!_.foldable))
+ val regularFunChildren = regularAggExprs
+ .flatMap(_.aggregateFunction.children.filter(!_.foldable))
+ val regularFilterAttrs = regularAggExprs.flatMap(_.filterAttributes)
+ val regularAggChildren = (regularFunChildren ++
regularFilterAttrs).distinct
+ val regularAggChildAttrMap =
regularAggChildren.map(expressionAttributePair)
+ val regularAggChildAttrLookup = regularAggChildAttrMap.toMap
+ val regularOperatorMap = regularAggExprs.map {
+ case ae @ AggregateExpression(af, _, _, filter, _) =>
+ val newChildren = af.children.map(c =>
regularAggChildAttrLookup.getOrElse(c, c))
+ val raf =
af.withNewChildren(newChildren).asInstanceOf[AggregateFunction]
+ val filterOpt = filter.map(_.transform {
+ case a: Attribute => regularAggChildAttrLookup.getOrElse(a, a)
+ })
+ val aggExpr = ae.copy(aggregateFunction = raf, filter = filterOpt)
+ (ae, aggExpr)
+ }
+ val distinctAggExprs = distinctAggExpressions.filter(e =>
e.children.exists(!_.foldable))
+ val rewriteDistinctOperatorMap = distinctAggExprs.zipWithIndex.map {
+ case (ae @ AggregateExpression(af, _, _, filter, _), i) =>
+ val phantomId = i + 1
Review comment:
The illusionary mechanism may result in multiple distinct aggregations uses
different column, so we still need to call `rewrite`. (e.g., `count(distinct
phantom1-a) and count(distinct a phantom2-a)`)
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