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From "Bryan Pendleton (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-4587) Add tools for improved analysis and understanding of query plans and execution statistics
Date Wed, 14 Jul 2010 14:27:50 GMT

    [ https://issues.apache.org/jira/browse/DERBY-4587?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12888361#action_12888361
] 

Bryan Pendleton commented on DERBY-4587:
----------------------------------------

Hi Nirmal,

I have a concern about the error-handling technique used in the patch.

In a number of places, particularly in AccessDatabase.java, but also in
some of the other classes, the code follows this pattern:

  try {
     ... do something ...
  } catch (SomeException e) {
     e.printStackTrace();
  }

I don't think this is the best pattern to use.

Instead, I think we should (a) remove the try/catch code from the method,
and (b) change the method's declaration to say "throws SomeException"

I suspect that, in general, the only try / catch block in the entire PlanExporter
code should probably be at the very outermost main() method. 

One exception to this is in the shutdown() method, where we do expect
to routinely catch and ignore the shutdown exception.

thanks,

bryan



> Add tools for improved analysis and understanding of query plans and execution statistics
> -----------------------------------------------------------------------------------------
>
>                 Key: DERBY-4587
>                 URL: https://issues.apache.org/jira/browse/DERBY-4587
>             Project: Derby
>          Issue Type: Improvement
>          Components: SQL, Tools
>            Reporter: Bryan Pendleton
>            Assignee: C.S. Nirmal J. Fernando
>         Attachments: basic_html-2.2.jpg, basic_html-2.3.jpg, basic_html-2.jpg, basic_html-3.jpg,
basic_html-4.1.jpg, basic_html-4.2.jpg, Derby Query Plan Screen Shot 2.jpg, DERBY-4587-tool-2.diff,
DERBY-4587-tool-3.diff, DERBY-4587-tool-4.diff, DERBY-4587-tool-5.diff, DERBY-4587-tool-6.diff,
DERBY-4587-tool-7-b.diff, DERBY-4587-tool-7.diff, DERBY-4587-tool-8.diff, DERBY-4587-tool-9.1.diff,
DERBY-4587-tool-9.2.diff, DERBY-4587-tool-9.diff, DERBY-4587-tool-test1.diff, DERBY-4587-tool-test2.diff,
DERBY-4587-tool.diff, Derby_Query_Plan_Screen_Shot.jpg, PostgreSQL license.jpg, Read_Me.txt,
screenshot-1.jpg, screenshot-2.jpg, screenshot-3.jpg, Simple HTML View (Pure XSL).jpg, Source.rar,
test.xml, test4.xsl, vanilla_html.xsl, vanilla_html.xsl, vanilla_html.xsl, vanilla_html.xsl,
xml_doc_screenshot.jpg, xml_doc_screenshot.jpg
>
>
> I think it would be great to see some work in the area of tools for helping
> with the analysis of complex query execution. Quite frequently, users of
> Derby have trouble comprehending (a) how their query is being translated
> into a query plan by the optimizer, and (b) what the execution-time resource
> usage of the various parts of the query is.
> There are low-level features in Derby which capture this information and
> record it, such as logQueryPlan, and the XPLAIN tables, but there is a lot
> of opportunity for designing higher-level tools which can process the query
> plan and execution statistics information and present it in a more
> comprehensible fashion. 

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