cloud-fan commented on a change in pull request #24223: [SPARK-27278][SQL]
Optimize GetMapValue when the map is a foldable and the key is not
URL: https://github.com/apache/spark/pull/24223#discussion_r271560401
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File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/ComplexTypes.scala
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@@ -59,6 +63,16 @@ object SimplifyExtractValueOps extends Rule[LogicalPlan] {
Literal(null, ga.dataType)
}
case GetMapValue(CreateMap(elems), key) => CaseKeyWhen(key, elems)
+ // The case below happens when the map is foldable, but the key is not,
so ConstantFolding
+ // converts the map in a Literal, but the GetMapValue is still there
since the key is not
+ // foldable. It cannot happen in any other case.
+ case GetMapValue(Literal(map: MapData, MapType(kt, vt, _)), key) if
!key.foldable =>
+ val elems = new mutable.ListBuffer[Literal]
+ map.foreach(kt, vt, (key, value) => {
+ elems.append(Literal(key, kt))
+ elems.append(Literal(value, vt))
+ })
+ CaseKeyWhen(key, elems.result())
Review comment:
Why is `CaseKeyWhen` faster than `GetMapValue`? they both do a linear scan
right?
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