Github user hvanhovell commented on a diff in the pull request:
https://github.com/apache/spark/pull/9409#discussion_r44213709
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Utils.scala
---
@@ -54,10 +54,14 @@ object Utils {
mode = aggregate.Complete,
isDistinct = false)
- // We do not support multiple COUNT DISTINCT columns for now.
- case expressions.CountDistinct(children) if children.length == 1 =>
+ case expressions.CountDistinct(children) =>
+ val child = if (children.size > 1) {
+ DropAnyNull(CreateStruct(children))
--- End diff --
@yhuai if we combine this with the distinct rewriting rule. It will add a
```struct``` to the groupBy clause of the first aggregate. This is currently
not allowed in the new UDAF path, so it'll fall back to the old path. For
example:
val data2 = Seq[(Integer, Integer, Integer)](
(1, 10, -10),
(null, -60, 60),
(1, 30, -30),
(1, 30, 30),
(2, 1, 1),
(null, -10, 10),
(2, -1, null),
(2, 1, 1),
(2, null, 1),
(null, 100, -10),
(3, null, 3),
(null, null, null),
(3, null, null)).toDF("key", "value1", "value2")
data2.registerTempTable("agg2")
val q sql(
"""
|SELECT
| key,
| count(distinct value1),
| count(distinct value2),
| count(distinct value1, value2)
|FROM agg2
|GROUP BY key
""".stripMargin)
Will create the following physical plan:
== Physical Plan ==
TungstenAggregate(key=[key#3], functions=[(count(if ((gid#44 = 1))
attributereference#45 else null),mode=Final,isDistinct=false),(count(if
((gid#44 = 3)) attributereference#47 else
null),mode=Final,isDistinct=false),(count(if ((gid#44 = 2)) dropanynull#46 else
null),mode=Final,isDistinct=false)], output=[key#3,_c1#32L,_c2#33L,_c3#34L])
TungstenExchange(Shuffle without coordinator)
hashpartitioning(key#3,200), None
TungstenAggregate(key=[key#3], functions=[(count(if ((gid#44 = 1))
attributereference#45 else null),mode=Partial,isDistinct=false),(count(if
((gid#44 = 3)) attributereference#47 else
null),mode=Partial,isDistinct=false),(count(if ((gid#44 = 2)) dropanynull#46
else null),mode=Partial,isDistinct=false)],
output=[key#3,count#49L,count#53L,count#51L])
Aggregate false,
[key#3,attributereference#45,dropanynull#46,attributereference#47,gid#44],
[key#3,attributereference#45,dropanynull#46,attributereference#47,gid#44]
ConvertToSafe
TungstenExchange(Shuffle without coordinator)
hashpartitioning(key#3,attributereference#45,dropanynull#46,attributereference#47,gid#44,200),
None
ConvertToUnsafe
Aggregate true,
[key#3,attributereference#45,dropanynull#46,attributereference#47,gid#44],
[key#3,attributereference#45,dropanynull#46,attributereference#47,gid#44]
!Expand [List(key#3, value1#4, null, null, 1),List(key#3, null,
dropanynull(struct(value1#4,value2#5)), null, 2),List(key#3, null, null,
value2#5, 3)],
[key#3,attributereference#45,dropanynull#46,attributereference#47,gid#44]
LocalTableScan [key#3,value1#4,value2#5],
[[1,10,-10],[null,-60,60],[1,30,-30],[1,30,30],[2,1,1],[null,-10,10],[2,-1,null],[2,1,1],[2,null,1],[null,100,-10],[3,null,3],[null,null,null],[3,null,null]]
Is it possible to add support for fixed width structs as group by
expression to the new aggregation path?
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