[
https://issues.apache.org/jira/browse/DERBY-4587?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12857821#action_12857821
]
Bryan Pendleton commented on DERBY-4587:
----------------------------------------
Hi! I think you are interpreting the XPLAIN table information accurately.
You can find additional information about the tables and columns of the XPLAIN
tables here:
http://db.apache.org/derby/docs/dev/tuning/ctun_xplain_tables.html
http://db.apache.org/derby/docs/dev/ref/rrefsysxplain_statements.html
http://db.apache.org/derby/docs/dev/ref/rrefsysxplain_statement_timings.html
http://db.apache.org/derby/docs/dev/ref/rrefsysxplain_resultsets.html
http://db.apache.org/derby/docs/dev/ref/rrefsysxplain_resultset_timings.html
http://db.apache.org/derby/docs/dev/ref/rrefsysxplain_scan_props.html
http://db.apache.org/derby/docs/dev/ref/rrefsysxplain_sort_props.html
> the query which tries to retrieve XPLAIN tables itself, is also stored in
> the XPLAIN tables again
Yes, this is expected behavior. To stop collecting XPLAIN information, call
the SET_XPLAIN_SHCEMA system procedure again, with an empty argument:
http://db.apache.org/derby/docs/dev/ref/rref_syscs_set_xplain_schema.html
> 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.
--
This message is automatically generated by JIRA.
-
If you think it was sent incorrectly contact one of the administrators:
https://issues.apache.org/jira/secure/Administrators.jspa
-
For more information on JIRA, see: http://www.atlassian.com/software/jira
