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https://issues.apache.org/jira/browse/SPARK-28298?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16880178#comment-16880178
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Yuming Wang commented on SPARK-28298:
-------------------------------------
PostgreSQL:
{code:sql}
postgres=# select substr(version(), 0, 16), cast('abcdef' as char(3));
substr | bpchar
-----------------+--------
PostgreSQL 11.3 | abc
(1 row)
{code}
Spark SQL:
{code:sql}
spark-sql> select cast('abcdef' as char(3));
abcdef
{code}
> Strange behavior of CAST string to char/varchar
> -----------------------------------------------
>
> Key: SPARK-28298
> URL: https://issues.apache.org/jira/browse/SPARK-28298
> Project: Spark
> Issue Type: Bug
> Components: SQL
> Affects Versions: 3.0.0
> Reporter: Zhu, Lipeng
> Priority: Major
>
> Execute below SQL in Spark, the result is "abcdef". But the result of other
> DBMS is "abc"(I think this is more sensible).
> {code:sql}
> select cast("abcdef" as char(3));
> {code}
> And then I checked the source code, seems char/varchar only be used in DDL
> parse.
> {code:java}
> /**
> * Hive char type. Similar to other HiveStringType's, these datatypes should
> only used for
> * parsing, and should NOT be used anywhere else. Any instance of these data
> types should be
> * replaced by a [[StringType]] before analysis.
> */
> case class CharType(length: Int) extends HiveStringType {
> override def simpleString: String = s"char($length)"
> }
> /**
> * Hive varchar type. Similar to other HiveStringType's, these datatypes
> should only used for
> * parsing, and should NOT be used anywhere else. Any instance of these data
> types should be
> * replaced by a [[StringType]] before analysis.
> */
> case class VarcharType(length: Int) extends HiveStringType {
> override def simpleString: String = s"varchar($length)"
> }
> {code}
> Is this behavior expected?
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