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From "Bryan Pendleton (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DERBY-6216) XPLAIN feature does not work and gives ERROR XCL16: ResultSet not open
Date Sat, 18 May 2013 15:45:16 GMT

    [ https://issues.apache.org/jira/browse/DERBY-6216?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13661379#comment-13661379
] 

Bryan Pendleton commented on DERBY-6216:
----------------------------------------

Urk. Sorry about that. At least the to-dos give us some idea of the scope of the problem.

It will require a fair bit of research to answer the questions you raise.

Interestingly it looks like, about 18 months ago, somebody else encountered
this and at the time I off-handedly answered without doing any research then, either:
http://apache-database.10148.n7.nabble.com/Statistics-are-not-capturing-in-XPLAIN-only-mode-td104392.html

The history of the development of this feature is primarily in DERBY-2487, but
it may be hard to contact the original contributor, as it has been more than 6 years
since this feature was implemented.

I do recall thinking at the time about the no-execute mode, but I don't recall
explicitly testing it in any detail, and I think if I had I would have included those
tests in the regression suite.

So perhaps I never really tested that behavior back then.
                
> XPLAIN feature does not work and gives ERROR XCL16: ResultSet not open
> ----------------------------------------------------------------------
>
>                 Key: DERBY-6216
>                 URL: https://issues.apache.org/jira/browse/DERBY-6216
>             Project: Derby
>          Issue Type: Bug
>          Components: Tools
>    Affects Versions: 10.6.2.3, 10.7.1.4, 10.8.3.1, 10.9.1.0
>         Environment: Solaris 10, MacOS X 10.6, Windows XP
>            Reporter: Brett Bergquist
>              Labels: features
>
> I am running Derby 10.9.1.0 and am trying to figure out a  performance problem with query
taking too long.   I don’t actually want to run the query so from the documentation, I try:
> call syscs_util.syscs_set_runtimestatistics(1);
> call syscs_util.syscs_set_xplain_schema('STATS');
> call syscs_util.syscs_set_xplain_mode(1);
> --- my query here
> call syscs_util.syscs_set_runtimestatistics(0);
> call syscs_util.syscs_set_xplain_schema('');
> call syscs_util.syscs_set_xplain_mode(0);
> When it runs my query, I get:
> ERROR XCL16: ResultSet not open. Operation 'getMetaData' not permitted. Verify that autocommit
is OFF.
> I try the following with IJ just to see:
> call syscs_util.syscs_set_runtimestatistics(1);
> call syscs_util.syscs_set_xplain_schema('STATS');
> call syscs_util.syscs_set_xplain_mode(1);
> select sql_text from syscs_diag.transaction_table where status != 'IDLE';
> call syscs_util.syscs_set_runtimestatistics(0);
> call syscs_util.syscs_set_xplain_schema('');
> call syscs_util.syscs_set_xplain_mode(0);
> Note I have tried this with real tables as apposed to the syscs_diag.transaction_table
with the same result.  The only reason that I posted this with this table is that it is a
table that is accessible for any database.

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