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https://issues.apache.org/jira/browse/DERBY-4587?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12856485#action_12856485
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A.S.Thiwanka Somasiri commented on DERBY-4587:
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Hi Bryan,
I read the Derby reference manual and Derby tuning materials to
some extent to get the scope for this project and got to know that all the
statistics that are logged into the logQueryPlan are stored in the XPLAIN
tables as well.One problem we had earlier was to find out all the statistic
data that can occur for a query.I studied the code for XPLAIN tables to some
extent and found that there are all the statistic variables that are stored in
the tables.So we can grab them from the source code.So it will be very easy to
get the values from the XPLAIN tables rather that retrieving them from the
derby.log file.
For example see the following package to understand the above desiption :
org.apache.derby.iapi.sql.execute.xplain
FYI : Read the "XPLAIN style tables" in Derby Reference Manual for more
information.
Thank you.
> 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: Bryan Pendleton
> Attachments: Derby Query Plan Screen Shot 2.jpg,
> 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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