GitHub user liancheng opened a pull request:
https://github.com/apache/spark/pull/3248
[SPARK-4322][SQL] Enables struct fields as sub expressions of grouping
fields
While resolving struct fields, the resulted `GetField` expression is
wrapped with an `Alias` to make it a named expression. Assume `a` is a struct
instance with a field `b`, then `"a.b"` will be resolved as `Alias(GetField(a,
"b"), "b")`. Thus, for this following SQL query:
```sql
SELECT a.b + 1 FROM t GROUP BY a.b + 1
```
the grouping expression is
```scala
Add(GetField(a, "b"), Literal(1, IntegerType))
```
while the aggregation expression is
```scala
Add(Alias(GetField(a, "b"), "b"), Literal(1, IntegerType))
```
This mismatch makes the above SQL query fail during the both analysis and
execution phases. This PR fixes this issue by removing the alias when
substituting aggregation expressions.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/liancheng/spark spark-4322
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/3248.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 #3248
----
commit 7f4653246647b32299b0f48414391323fcd4273a
Author: Cheng Lian <l...@databricks.com>
Date: 2014-11-13T16:34:09Z
Enables struct fields as sub expressions of grouping fields
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