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https://issues.apache.org/jira/browse/SPARK-25824?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16662725#comment-16662725
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Dongjoon Hyun commented on SPARK-25824:
---------------------------------------

[~srowen]. Please see the description. The string notation is just a collection 
of the stored data.
`[1 -> 2, 1 -> 3]`

If you materialize that string to `map` again, the result will be `1->3` 
eventually. In that sense, I didn't categorize this as a bug.
{code}
scala> Map(1->2,1->3)
res5: scala.collection.immutable.Map[Int,Int] = Map(1 -> 3)
{code}

> Remove duplicated map entries in `showString`
> ---------------------------------------------
>
>                 Key: SPARK-25824
>                 URL: https://issues.apache.org/jira/browse/SPARK-25824
>             Project: Spark
>          Issue Type: Improvement
>          Components: SQL
>    Affects Versions: 3.0.0
>            Reporter: Dongjoon Hyun
>            Priority: Minor
>
> `showString` doesn't eliminate the duplication. So, it looks different from 
> the result of `collect` and select from saved rows.
> *Spark 2.2.2*
> {code}
> spark-sql> select map(1,2,1,3);
> {1:3}
> scala> sql("SELECT map(1,2,1,3)").collect
> res0: Array[org.apache.spark.sql.Row] = Array([Map(1 -> 3)])
> scala> sql("SELECT map(1,2,1,3)").show
> +---------------+
> |map(1, 2, 1, 3)|
> +---------------+
> |    Map(1 -> 3)|
> +---------------+
> {code}
> *Spark 2.3.0 ~ 2.4.0-rc4*
> {code}
> spark-sql> select map(1,2,1,3);
> {1:3}
> scala> sql("SELECT map(1,2,1,3)").collect
> res1: Array[org.apache.spark.sql.Row] = Array([Map(1 -> 3)])
> scala> sql("CREATE TABLE m AS SELECT map(1,2,1,3) a")
> scala> sql("SELECT * FROM m").show
> +--------+
> |       a|
> +--------+
> |[1 -> 3]|
> +--------+
> scala> sql("SELECT map(1,2,1,3)").show
> +----------------+
> | map(1, 2, 1, 3)|
> +----------------+
> |[1 -> 2, 1 -> 3]|
> +----------------+
> {code}



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