[jira] [Commented] (SPARK-26869) UDF with struct requires to have _1 and _2 as struct field names

["Valeria Vasylieva (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SPARK-26869?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16772988#comment-16772988 ] 

Valeria Vasylieva commented on SPARK-26869:
-------------------------------------------

[~anddonram] you are trying to treat Struct as Tuple in udf, but even if you try to use Row/case class, it will also fail as it is not supported yet.

Try to look at [SPARK-12823|https://issues.apache.org/jira/browse/SPARK-12823], it seems to be related. Hope it helps.

 

> UDF with struct requires to have _1 and _2 as struct field names
> ----------------------------------------------------------------
>
>                 Key: SPARK-26869
>                 URL: https://issues.apache.org/jira/browse/SPARK-26869
>             Project: Spark
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 2.3.0, 2.4.0
>         Environment: Ubuntu 18.04.1 LTS
>            Reporter: Andrés Doncel Ramírez
>            Priority: Minor
>
> When using a UDF which has a Seq of tuples as input, the struct field names need to match "_1" and "_2". The following code illustrates this:
>  
> {code:java}
> val df = sc.parallelize(Array(
>   ("1",3.0),
>   ("2",4.5),
>   ("5",2.0)
> )
> ).toDF("c1","c2")
> val df1=df.agg(collect_list(struct("c1","c2")).as("c3"))
> // Changing column names to _1 and _2 when creating the struct
> val df2=df.agg(collect_list(struct(col("c1").as("_1"),col("c2").as("_2"))).as("c3"))
> def takeUDF = udf({ (xs: Seq[(String, Double)]) =>
>   xs.take(2)
> })
> df1.printSchema
> df2.printSchema
> df1.withColumn("c4",takeUDF(col("c3"))).show() // this fails
> df2.withColumn("c4",takeUDF(col("c3"))).show() // this works
> {code}
> The first one returns the following exception:
> org.apache.spark.sql.AnalysisException: cannot resolve 'UDF(c3)' due to data type mismatch: argument 1 requires array<struct<_1:string,_2:double>> type, however, '`c3`' is of array<struct<c1:string,c2:double>> type.;;
> While the second works as expected and prints the result.



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