GitHub user gatorsmile opened a pull request:
https://github.com/apache/spark/pull/18574
[SPARK-21350] [SQL] Fix the error message when the number of arguments is
wrong when invoking a UDF
### What changes were proposed in this pull request?
Users get a very confusing error when users specify a wrong number of
parameters.
```Scala
val df = spark.emptyDataFrame
spark.udf.register("foo", (_: String).length)
df.selectExpr("foo(2, 3, 4)")
```
```
org.apache.spark.sql.UDFSuite$$anonfun$9$$anonfun$apply$mcV$sp$12 cannot be
cast to scala.Function3
java.lang.ClassCastException:
org.apache.spark.sql.UDFSuite$$anonfun$9$$anonfun$apply$mcV$sp$12 cannot be
cast to scala.Function3
at
org.apache.spark.sql.catalyst.expressions.ScalaUDF.<init>(ScalaUDF.scala:109)
```
This PR is to capture the exception and issue an error message that is
consistent with what we did for built-in functions. After the fix, the error
message is improved to
```
Invalid number of arguments for function foo; line 1 pos 0
org.apache.spark.sql.AnalysisException: Invalid number of arguments for
function foo; line 1 pos 0
at
org.apache.spark.sql.catalyst.analysis.SimpleFunctionRegistry.lookupFunction(FunctionRegistry.scala:119)
```
### How was this patch tested?
Added a test case
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/gatorsmile/spark statsCheck
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/18574.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 #18574
----
commit 8302c2a11efa1f444c2b69999fcc94ee4356d2ea
Author: gatorsmile <[email protected]>
Date: 2017-07-09T03:46:32Z
fix.
----
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