[jira] [Commented] (SPARK-14488) Weird behavior of DDL "CREATE TEMPORARY TABLE ... USING ... AS SELECT ..."

["Cheng Lian (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SPARK-14488?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15232078#comment-15232078 ] 

Cheng Lian commented on SPARK-14488:
------------------------------------

Updated title and description of this ticket.

> Weird behavior of DDL "CREATE TEMPORARY TABLE ... USING ... AS SELECT ..."
> --------------------------------------------------------------------------
>
>                 Key: SPARK-14488
>                 URL: https://issues.apache.org/jira/browse/SPARK-14488
>             Project: Spark
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 2.0.0
>            Reporter: Cheng Lian
>            Assignee: Cheng Lian
>
> Currently, Spark 2.0 master allows DDL statements like {{CREATE TEMPORARY TABLE ... USING ... AS SELECT ...}}, which imposes weird behavior and weird semantics.
> Let's try the following Spark shell snippet:
> {code}
> sqlContext range 10 registerTempTable "x"
> // The problematic DDL statement:
> sqlContext sql "CREATE TEMPORARY TABLE y USING PARQUET AS SELECT * FROM x"
> sqlContext.tables().show()
> {code}
> It shows the following result:
> {noformat}
> +---------+-----------+
> |tableName|isTemporary|
> +---------+-----------+
> |        y|      false|
> |        x|       true|
> +---------+-----------+
> {noformat}
> *Weird behavior*
> Note that {{y}} is NOT temporary although it's created using {{CREATE TEMPORARY TABLE ...}}, and the query result is written in Parquet format under default Hive warehouse location, which is {{/user/hive/warehouse/y}} on my local machine.
> *Weird semantics*
> Secondly, even if this DDL statement does create a temporary table, the semantics is still somewhat weird:
> # It has a {{AS SELECT ...}} clause, which is supposed to run a given query instead of loading data from existing files.
> # It has a {{USING <format>}} clause, which is supposed to, I guess, converting the result of the above query into the given format. And by "converting", we have to write out the data into file system.
> # It has a {{TEMPORARY}} keyword, which is supposed to, I guess, create an in-memory temporary table using the files written above?
> The main questions:
> # Is the above combination ({{TEMPORARY}} + {{USING}} + {{AS SELECT}}) a valid one?
> # If it is, what is the expected semantics?



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)

---------------------------------------------------------------------
To unsubscribe, e-mail: issues-unsubscribe@spark.apache.org
For additional commands, e-mail: issues-help@spark.apache.org