GitHub user clockfly opened a pull request:
https://github.com/apache/spark/pull/14616
[SPARK-16955][SQL] Fix analysis error when using ordinal in ORDER BY or
GROUP BY
## What changes were proposed in this pull request?
This PR adds two unresolved expressions to represent the ordinal in GROUP
BY or ORDER BY `GroupByOrdinal` and `OrderByOrdinal`, and fixes the rules when
resolving ordinals.
Ordinals in GROUP BY or ORDER BY like `1` in `order by 1` or `group by 1`
should be considered as unresolved expressions before analysis. But in current
code, it is represented as a `Literal` expression directly, which is a resolved
expression. It may cause analysis failure if a rule requires the ordinal to be
resolved before applying.
**For example:**
Before this fix, rule `ResolveAggregateFunctions` will try to resolve the
`Filter` before `Filter`'s child `Aggregate` is fully resolved (`Aggregate`
contains an unresolved group by ordinal `2`)
```
'Filter ('a > 0)
+- Aggregate [2], [count(1) AS count(1)#83L, a#81]
+- SubqueryAlias tmp
+- Project [1 AS a#81]
+- OneRowRelation$
```
### Before this change
Ordinal is stored as `Literal` expression
```
scala> sc.setLogLevel("TRACE")
scala> sql("select a from t group by 1 order by 1")
...
'Sort [1 ASC], true
+- 'Aggregate [1], ['a]
+- 'UnresolvedRelation `t
```
And it causes analysis error when applying rule ResolveAggregateFunctions,
as group by ordinal `2` claim to have been resolved, but is not resolved
actually.
```
scala> Seq(1).toDF("a").createOrReplaceTempView("t")
scala> sql("select count(a), a from t group by 2 having a > 0").show
org.apache.spark.sql.catalyst.analysis.UnresolvedException: Invalid call to
Group by position: '2' exceeds the size of the select list '1'. on unresolved
object, tree:
Aggregate [2], [(a#9 > 0) AS havingCondition#15]
+- SubqueryAlias t
+- Project [value#7 AS a#9]
+- LocalRelation [value#7]
...
```
### After this change
Ordinals are stored as `GroupByOrdinal` or `OrderByOrdinal`.
```
scala> sc.setLogLevel("TRACE")
scala> sql("select a from t group by 1 order by 1")
...
'Sort [orderbyordinal(1) ASC], true
+- 'Aggregate [groupbyordinal(1)], ['a]
+- 'UnresolvedRelation `t`
```
And rule ResolveAggregateFunctions can be safely applied as we have
explicitly resolved `GroupByOrdinal(2)` before applying this rule.
```
scala> Seq(1).toDF("a").createOrReplaceTempView("t")
scala> sql("select count(a), a from t group by 2 having a > 0").show
+--------+---+
|count(a)| a|
+--------+---+
| 1| 1|
+--------+---+
```
## How was this patch tested?
Unit tests.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/clockfly/spark spark-16955
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/14616.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 #14616
----
commit 40873650c7397a339210092f616c15aedbf13b17
Author: Sean Zhong <seanzh...@databricks.com>
Date: 2016-08-08T21:40:53Z
[SPARK-16955][SQL] Fix analysis error when using ordinal in ORDER BY or
GROUP BY
----
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