[jira] [Commented] (CALCITE-1801) RelRunners connection garbage-collected prematurely

["JD Zheng (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-1801?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16020014#comment-16020014 ] 

JD Zheng commented on CALCITE-1801:
-----------------------------------

comments from Julian:

"Maybe we use some callback to create a connection. And maybe if you are using an anonymous class it causes the connection to be garbage-collected sooner."

> RelRunners connection garbage-collected prematurely
> ---------------------------------------------------
>
>                 Key: CALCITE-1801
>                 URL: https://issues.apache.org/jira/browse/CALCITE-1801
>             Project: Calcite
>          Issue Type: Bug
>          Components: core
>    Affects Versions: 1.13.0
>         Environment: osx 10.11.6, JavaSE-1.8, junit-4.12
>            Reporter: JD Zheng
>            Assignee: Julian Hyde
>            Priority: Minor
>
> I am using RelRunners to execute pre-built relnode tree. It works perfectly when I put the following code in the junit class:
>    protected String execute(RelNode rel) {
>         try (final PreparedStatement preparedStatement = RelRunners.run(rel)) {
>           final ResultSet resultSet = preparedStatement.executeQuery();
>           return printResult(resultSet, true);
>         } catch (SQLException e) {
>           throw new RuntimeException(e);
>         }
>     }
> However,if I put these code inside a src class, the returned resultSet is closed.
> More interestingly, if I expand the RelRunners.run() in the method like this:
>    public static ResultSet execute(RelNode rel) {
> 	/*
>         try (final PreparedStatement preparedStatement = RelRunners.run(rel)) {
>           return preparedStatement.executeQuery();
>         } catch (SQLException e) {
>           throw new AQLExecuteErrorException(e);
>         }
>         */
>         try (Connection connection = DriverManager.getConnection("jdbc:calcite:")) {
>             final RelRunner runner = connection.unwrap(RelRunner.class);
>             PreparedStatement preparedStatement = runner.prepare(rel);
>             return preparedStatement.executeQuery();
>           } catch (SQLException e) {
>             throw new AQLExecuteErrorException(e);
>           }
>     }
> It works again. 



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