GitHub user hvanhovell opened a pull request:
https://github.com/apache/spark/pull/15076
[SPARK-17114][SQL] Fix aggregates grouped by literals with empty input.
## What changes were proposed in this pull request?
This PR fixes an issue with aggregates that have an empty input, and use a
literals as their grouping keys. These aggregates are currently interpreted as
aggregates **without** grouping keys, this triggers the ungrouped code path
(which aways returns a single row).
This PR fixes this by adding a `isGrouped` flag to `Aggregate`. This flag
is inferred when the `Aggregate` is created, but is kept when we change the
`Aggregate`s grouping expressions. I have tried to implement this by wrapping
the `groupingExpressions` in an `Option` but this is much more invasive and
leads to much harder to use code.
## How was this patch tested?
Added tests to `SQLQueryTestSuite`.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/hvanhovell/spark SPARK-17114-2
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/15076.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 #15076
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commit f8f1ebb2c10fab8c02d37ec6f3bf667f34fea762
Author: Herman van Hovell <[email protected]>
Date: 2016-09-13T08:54:54Z
fix aggregates that are grouped by a literal with empty input.
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