[jira] [Commented] (SPARK-21997) Spark shows different results on Hive char/varchar columns on Parquet/ORC

["Dongjoon Hyun (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SPARK-21997?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16165096#comment-16165096 ] 

Dongjoon Hyun commented on SPARK-21997:
---------------------------------------

Hi, [~smilegator] and [~cloud_fan].
I'm wondering if this is designed like this because it seems to be a behavior since 2.0.
Since this is a configuration issue, should we turn off `spark.sql.hive.convertMetastoreParquet` or make a fix for this?

> Spark shows different results on Hive char/varchar columns on Parquet/ORC
> -------------------------------------------------------------------------
>
>                 Key: SPARK-21997
>                 URL: https://issues.apache.org/jira/browse/SPARK-21997
>             Project: Spark
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 2.0.2, 2.1.1, 2.2.0
>            Reporter: Dongjoon Hyun
>
> SPARK-19459 resolves CHAR/VARCHAR issues in general, but Spark shows different results according to the SQL configuration, `spark.sql.hive.convertMetastoreParquet`. We had better fix this. Actually, the default of `spark.sql.hive.convertMetastoreParquet` is true, so the result is wrong by default. For ORC, the default of `spark.sql.hive.convertMetastoreParquet` is false, so SPARK-19459 didn't resolve this together. For ORC, it will happen if we turn on it `true`.
> {code}
> hive> CREATE TABLE t_char(a CHAR(10), b VARCHAR(10)) STORED AS parquet;
> hive> INSERT INTO TABLE t_char SELECT 'a', 'b' FROM (SELECT 1) t;
> scala> sql("SELECT * FROM t_char").show
> +---+---+
> |  a|  b|
> +---+---+
> |  a|  b|
> +---+---+
> scala> sql("set spark.sql.hive.convertMetastoreParquet=false")
> scala> sql("SELECT * FROM t_char").show
> +----------+---+
> |         a|  b|
> +----------+---+
> |a         |  b|
> +----------+---+
> scala> spark.version
> res3: String = 2.2.0
> {code}



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