GitHub user maropu opened a pull request:
https://github.com/apache/spark/pull/17400
[SPARK-19981][SQL] Update output partitioning info. in ProjectExec when
having aliases
## What changes were proposed in this pull request?
The current master wrongly adds `ShuffleExchange` when operator's
`requiredChildDistribution` refers to aliases. A concrete example is as follows;
```
scala> :paste
sql("SET spark.sql.autoBroadcastJoinThreshold=-1")
spark.range(10).selectExpr("id AS key",
"0").repartition($"key").createOrReplaceTempView("df1")
spark.range(10).selectExpr("id AS key",
"0").repartition($"key").createOrReplaceTempView("df2")
sql("""
SELECT * FROM
(SELECT key AS k from df1) t1
INNER JOIN
(SELECT key AS k from df2) t2
ON t1.k = t2.k
""").explain
== Physical Plan ==
*SortMergeJoin [k#56L], [k#57L], Inner
:- *Sort [k#56L ASC NULLS FIRST], false, 0
: +- Exchange hashpartitioning(k#56L, 200) // <--- Unnecessary
ShuffleExchange
: +- *Project [key#39L AS k#56L]
: +- Exchange hashpartitioning(key#39L, 200)
: +- *Project [id#36L AS key#39L]
: +- *Range (0, 10, step=1, splits=Some(4))
+- *Sort [k#57L ASC NULLS FIRST], false, 0
+- ReusedExchange [k#57L], Exchange hashpartitioning(k#56L, 200)
```
In the query, the second `Exchange` is not necessary. The root cause is
that the planner wrongly regards `key` and `k` as different attributes because
they have different `exprId`. Then, it fails distribution checks in
`EnsureRequirements`. This pr is to update output partitioning info. in
`ProjectExec` when projection lists having aliases.
## How was this patch tested?
Added tests in `SQLQueryTestSuite`.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/maropu/spark SPARK-19981
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/17400.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 #17400
----
commit b5d1038edffff5d65a6ddec20ea6eef186d25fc3
Author: Takeshi Yamamuro <[email protected]>
Date: 2017-03-23T16:12:28Z
Update partitioning info. in ProjectExec when having aliases
----
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