GitHub user jiangxb1987 opened a pull request:
https://github.com/apache/spark/pull/15672
[SPARK-18148][SQL] Misleading Error Message for Aggregation Without
Window/GroupBy
## What changes were proposed in this pull request?
Aggregation Without Window/GroupBy expressions will fail in
`checkAnalysis`, the error message is a bit misleading, we should generate a
more specific error message for this case.
For example,
```
spark.read.load("/some-data")
.withColumn("date_dt", to_date($"date"))
.withColumn("year", year($"date_dt"))
.withColumn("week", weekofyear($"date_dt"))
.withColumn("user_count", count($"userId"))
.withColumn("daily_max_in_week", max($"user_count").over(weeklyWindow))
)
```
creates the following output:
```
org.apache.spark.sql.AnalysisException: expression '`randomColumn`' is
neither present in the group by, nor is it an aggregate function. Add to group
by or wrap in first() (or first_value) if you don't care which value you get.;
```
In the error message above, `randomColumn` doesn't appear in the
query(acturally it's added by function `withColumn`), so the message is not
enough for the user to address the problem.
## How was this patch tested?
Manually test
Before:
```
scala> spark.sql("select col, count(col) from tbl")
org.apache.spark.sql.AnalysisException: expression 'tbl.`col`' is neither
present in the group by, nor is it an aggregate function. Add to group by or
wrap in first() (or first_value) if you don't care which value you get.;;
```
After:
```
scala> spark.sql("select col, count(col) from tbl")
org.apache.spark.sql.AnalysisException: grouping expressions sequence is
empty, and 'tbl.`col`' is not an aggregate function. Wrap '(count(col#231L) AS
count(col)#239L)' in windowing function(s) or wrap 'tbl.`col`' in first() (or
first_value) if you don't care which value you get.;;
```
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/jiangxb1987/spark groupBy-empty
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/15672.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 #15672
----
commit 494ef0931b6c8e0a4c0804f88a21b7dce7870750
Author: jiangxingbo <jiangxb1...@gmail.com>
Date: 2016-10-28T10:48:21Z
improve error message when checkAnalysis fail on Aggregate operator.
commit 350b7a335038adbe8a5a766d7a77fa17db0dbdeb
Author: jiangxingbo <jiangxb1...@gmail.com>
Date: 2016-10-28T11:12:04Z
better format.
----
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