Github user marmbrus commented on a diff in the pull request:
https://github.com/apache/spark/pull/683#discussion_r12404117
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregates.scala
---
@@ -86,6 +86,67 @@ abstract class AggregateFunction
override def newInstance() = makeCopy(productIterator.map { case a:
AnyRef => a }.toArray)
}
+case class Min(child: Expression) extends PartialAggregate with
trees.UnaryNode[Expression] {
+ override def references = child.references
+ override def nullable = child.nullable
+ override def dataType = child.dataType
+ override def toString = s"MIN($child)"
+
+ override def asPartial: SplitEvaluation = {
+ val partialMin = Alias(Min(child), "PartialMin")()
+ SplitEvaluation(Min(partialMin.toAttribute), partialMin :: Nil)
+ }
+
+ override def newInstance() = new MinFunction(child, this)
+}
+
+case class MinFunction(expr: Expression, base: AggregateExpression)
extends AggregateFunction {
--- End diff --
Good point, though this is not an issue in the code gen version.
On May 7, 2014 2:28 PM, "Reynold Xin" <[email protected]> wrote:
> In
>
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregates.scala:
>
> > @@ -86,6 +86,67 @@ abstract class AggregateFunction
> > override def newInstance() = makeCopy(productIterator.map { case a:
AnyRef => a }.toArray)
> > }
> >
> > +case class Min(child: Expression) extends PartialAggregate with
trees.UnaryNode[Expression] {
> > + override def references = child.references
> > + override def nullable = child.nullable
> > + override def dataType = child.dataType
> > + override def toString = s"MIN($child)"
> > +
> > + override def asPartial: SplitEvaluation = {
> > + val partialMin = Alias(Min(child), "PartialMin")()
> > + SplitEvaluation(Min(partialMin.toAttribute), partialMin :: Nil)
> > + }
> > +
> > + override def newInstance() = new MinFunction(child, this)
> > +}
> > +
> > +case class MinFunction(expr: Expression, base: AggregateExpression)
extends AggregateFunction {
>
> this is unrelated to this pr - but I just realized the way we are storing
> the aggregation buffer in Spark SQL uses much more memory than needed,
> because there are two extra pointers to expr/base, which is identical for
> every tuple.
>
> â
> Reply to this email directly or view it on
GitHub<https://github.com/apache/spark/pull/683/files#r12404003>
> .
>
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