Github user marmbrus commented on the pull request:
https://github.com/apache/spark/pull/9202#issuecomment-152648785
You have to put the subquery in parentheses so it results in valid SQL.
On Oct 30, 2015 9:06 PM, "Rick Hillegas" <notificati...@github.com> wrote:
> Thanks for that feedback, Michael. To answer your question:
>
> MA> I haven't looked closely at the implementation, but one high level
> question is whether this is breaking the use case where a users gives a
> subquery instead of a table name (i.e. dbtable = (SELECT ...).) This is an
> important part of the API that we can't break.
>
> Reynold posed the same question at
>
https://issues.apache.org/jira/browse/SPARK-10857?focusedCommentId=14967827&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-14967827
> and I replied at
>
https://issues.apache.org/jira/browse/SPARK-10857?focusedCommentId=14967930&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-14967930
>
> Can you give me an example of the syntax you have in mind which might trip
> this problem? I tried the following experiment...
>
> val jdbcDF = sqlContext.read.format("jdbc").options(
> Map("url" -> "jdbc:derby:/Users/rhillegas/derby/databases/derby1",
> "dbtable" -> "select * from app.t")).load()
>
> ...but that statement doesn't tickle JdbcDialect.getTableExistsQuery().
> Instead, the statement fails because the following ungrammatical query is
> sent to the database:
>
> SELECT * FROM select * from app.t WHERE 1=0
>
> That, in turn, is because JDBCRDD.resolveTable() has its own hard-coded
> query which probes for the existence of a table. I have logged
> https://issues.apache.org/jira/browse/SPARK-11426 to track this issue.
> The header comment on JDBCRDD.resolveTable() indicates that the method
> expects a table name and not an arbitrary query.
>
> Thanks,
> -Rick
>
> â
> Reply to this email directly or view it on GitHub
> <https://github.com/apache/spark/pull/9202#issuecomment-152638711>.
>
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