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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 Sat, 29 May 2010 21:59:36 GMT

    [ https://issues.apache.org/jira/browse/DERBY-4587?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12873334#action_12873334

Bryan Pendleton commented on DERBY-4587:

I successfully applied and built the test, and ran the XML generation tool (once). 
Great work! This is very exciting!

Some first comments:
1) I had some trouble running the tool, until I realized that the tool was always
loading the ClientDriver, and I was trying to create an embedded connection. I
think we want to support both client-style URLs and embedded-style URLs, so
we need a way to detect which connection URL is provided, and load the
appropriate driver.

2) I had to apply the patch from the 'java' directory; it is more conventional to
create patches to be applied from the 'trunk' directory.

3) I just tried the generation tool with a very simple query in my XPLAIN tables,
and it seemed to work. If I get a chance, I'll try to run it against some other XPLAIN output.

4) I'm not sure that it is helpful for the AccessDatabase class to be catching
the SQLException errors; it might be better to declare those methods as
throwing the exceptions and let the exceptions propagate out.

5) I found the code in createXMLFragment() a bit hard to read; perhaps it
would be a bit more legible if the long lines were broken up into multiple
shorter lines?

6) Have you had a chance to think about how we might go about building
a regression test suite for the new tool? One possibility would be to extend
the current XplainStatisticsTest so that, in addition to generating XPLAIN
data for various query plans, that test also calls your new tool to format the
data as XML, then checks the XML documents for correctness.

> 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: Derby Query Plan Screen Shot 2.jpg, DERBY-4587-tool.diff, Derby_Query_Plan_Screen_Shot.jpg,
PostgreSQL license.jpg, Read_Me.txt, Source.rar
> 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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