GitHub user maropu opened a pull request:
https://github.com/apache/spark/pull/10896
[SPARK-12978][SQL] Skip unnecessary final group-by when input data already
clustered with group-by keys
This ticket targets the optimization to skip an unnecessary group-by
operation below;
Without opt.:
```
== Physical Plan ==
TungstenAggregate(key=[col0#159],
functions=[(sum(col1#160),mode=Final,isDistinct=false),(avg(col2#161),mode=Final,isDistinct=false)],
output=[col0#159,sum(col1)#177,avg(col2)#178])
+- TungstenAggregate(key=[col0#159],
functions=[(sum(col1#160),mode=Partial,isDistinct=false),(avg(col2#161),mode=Partial,isDistinct=false)],
output=[col0#159,sum#200,sum#201,count#202L])
+- TungstenExchange hashpartitioning(col0#159,200), None
+- InMemoryColumnarTableScan [col0#159,col1#160,col2#161],
InMemoryRelation [col0#159,col1#160,col2#161], true, 10000, StorageLevel(true,
true, false, true, 1), ConvertToUnsafe, None
```
With opt.:
```
== Physical Plan ==
TungstenAggregate(key=[col0#159],
functions=[(sum(col1#160),mode=Complete,isDistinct=false),(avg(col2#161),mode=Final,isDistinct=false)],
output=[col0#159,sum(col1)#177,avg(col2)#178])
+- TungstenExchange hashpartitioning(col0#159,200), None
+- InMemoryColumnarTableScan [col0#159,col1#160,col2#161],
InMemoryRelation [col0#159,col1#160,col2#161], true, 10000, StorageLevel(true,
true, false, true, 1), ConvertToUnsafe, None
```
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/maropu/spark SkipGroupbySpike
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/10896.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #10896
----
commit 5ab19c1a97593b75512ba7b910849bef87f9810e
Author: Takeshi YAMAMURO <linguin....@gmail.com>
Date: 2016-01-25T05:58:45Z
Skip unnecessary final group-by when input data already clustered
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