[jira] [Commented] (SPARK-26372) CSV parsing uses previous good value for bad input field

["Bruce Robbins (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SPARK-26372?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16721593#comment-16721593 ] 

Bruce Robbins commented on SPARK-26372:
---------------------------------------

I can prep a PR, unless someone thinks this needs a different solution than the one I proposed.

> CSV parsing uses previous good value for bad input field
> --------------------------------------------------------
>
>                 Key: SPARK-26372
>                 URL: https://issues.apache.org/jira/browse/SPARK-26372
>             Project: Spark
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 3.0.0
>            Reporter: Bruce Robbins
>            Priority: Major
>
> For example:
> {noformat}
> bash-3.2$ cat test.csv 
> "hello",1999-08-01
> "there","bad date"
> "again","2017-11-22"
> bash-3.2$ bin/spark-shell
> ..etc..
> scala> import org.apache.spark.sql.types._
> scala> import org.apache.spark.sql.SaveMode
> scala> var schema = StructType(StructField("col1", StringType) ::
>      |   StructField("col2", DateType) ::
>      |   Nil)
> schema: org.apache.spark.sql.types.StructType = StructType(StructField(col1,StringType,true), StructField(col2,DateType,true))
> scala> val df = spark.read.schema(schema).csv("test.csv")
> df: org.apache.spark.sql.DataFrame = [col1: string, col2: date]
> scala> df.show
> +-----+----------+                                                              
> | col1|      col2|
> +-----+----------+
> |hello|1999-08-01|
> |there|1999-08-01|
> |again|2017-11-22|
> +-----+----------+
> scala> 
> {noformat}
> col2 from the second row contains "1999-08-01", when it should contain null.
> This is because UnivocityParser reuses the same Row object for each input record. If there is an exception converting an input field, the code simply skips over that field, leaving the existing value in the Row object.
> The simple fix is to set the column to null in the Row object whenever there is a badRecordException while converting the input field.



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