Github user hvanhovell commented on a diff in the pull request:
https://github.com/apache/spark/pull/10067#discussion_r46353257
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala
---
@@ -223,10 +223,13 @@ class Analyzer(
case other => Alias(other, other.toString)()
}
- // TODO: We need to use bitmasks to determine which grouping
expressions need to be
- // set as nullable. For example, if we have GROUPING SETS ((a,b),
a), we do not need
- // to change the nullability of a.
- val attributeMap = groupByAliases.map(a => (a ->
a.toAttribute.withNullability(true))).toMap
+ val attributeMap = groupByAliases.zipWithIndex.map { case (a, idx)
=>
+ if (x.bitmasks.exists(bitmask => (bitmask & 1 << idx) == 0)) {
+ (a -> a.toAttribute.withNullability(true))
+ } else {
+ (a -> a.toAttribute)
+ }
+ }.toMap
--- End diff --
It is the same thing. I only suggested to aggregate the bitmap in advance:
```val nonNullBitmask = x.bitmasks.reduce(_ & _)``` and to use the
```nonNullBitmask``` to check for (non) nullability in the loop. It should be a
tiny tiny tiny bit quicker (no re-iteration required , and less one closure).
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