ravipesala commented on a change in pull request #3129: [CARBONDATA-3295] Fix
that MV datamap throw exception because its rewrite algorithm when query SQL
has multiply subquery
URL: https://github.com/apache/carbondata/pull/3129#discussion_r282844915
##########
File path:
datamap/mv/core/src/main/scala/org/apache/carbondata/mv/datamap/MVHelper.scala
##########
@@ -596,12 +596,20 @@ object MVHelper {
case g: GroupBy =>
MVHelper.updateDataMap(g, rewrite)
}
- // TODO Find a better way to set the rewritten flag, it may fail in some
conditions.
- val mapping =
- rewrittenPlan.collect { case m: ModularPlan => m } zip
- updatedDataMapTablePlan.collect { case m: ModularPlan => m }
- mapping.foreach(f => if (f._1.rewritten) f._2.setRewritten())
+ // Use coarse equal to set the rewritten flag
+ // We may change the ModularPlan relation
+ // So we match the node excluding child comparison
+ updatedDataMapTablePlan.map(plan => {
+ if (rewrittenPlan.find (
+ oriPlan => oriPlan.rewritten && (plan match {
+ case select: Select => select.coarseEqual(oriPlan)
Review comment:
It will unnecessarily add the processing to check the equals of all
relations here. It is better we can remove this code completely and add the
following.
MVHelper
```
def rewriteWithMVTable(rewrittenPlan: ModularPlan, rewrite: QueryRewrite):
ModularPlan = {
if (rewrittenPlan.find(_.rewritten).isDefined) {
val updatedDataMapTablePlan = rewrittenPlan transform {
case s: Select =>
MVHelper.updateDataMap(s, rewrite)
case g: GroupBy =>
MVHelper.updateDataMap(g, rewrite)
}
updatedDataMapTablePlan
} else {
rewrittenPlan
}
}
```
Add new method in org.apache.carbondata.mv.plans.modular.GroupBy
```
override def makeCopy(newArgs: Array[AnyRef]): GroupBy = {
val groupBy = super.makeCopy(newArgs).asInstanceOf[GroupBy]
if (rewritten) groupBy.setRewritten()
groupBy
}
```
Add new method in org.apache.carbondata.mv.plans.modular.Select
```
override def makeCopy(newArgs: Array[AnyRef]): Select = {
val select = super.makeCopy(newArgs).asInstanceOf[Select]
if (rewritten) select.setRewritten()
select
}
```
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