Comments on: GATHER_PLAN_STATISTICS

By: Articles from Kerry Osborne | Chen Guang's Blog

Articles from Kerry Osborne | Chen Guang's Blog — Mon, 21 Mar 2011 23:45:04 +0000

[...] GATHER_PLAN_STATISTICS February 9, 2010, 12:02 pm [...]

By: Uday

Uday — Thu, 06 Jan 2011 17:33:01 +0000

Very clever trick! Thanks a lot for sharing. We are seeing quite a lot of overhead with tracing in 11g, especially when we have slow-by-slow (i.e., row-by-row) processing. So, this trick would a lot. With this trick and Real-Time SQL Monitoring we would not miss a expensive (expensive is very subjective) SQL.

Thanks!

By: Kerry Osborne’s Oracle Blog » Blog Archive Interaction Between Baselines and Profiles – Kerry Osborne’s Oracle Blog

Fri, 10 Dec 2010 16:32:23 +0000

[...] a previous post (GATHER_PLAN_STATISTICS) I mentioned that SQL Profiles and Baselines can both be applied to a single statement. In this [...]

By: Great GATHER_PLAN_STATISTICS Example Article « Gerry Christiansen

Great GATHER_PLAN_STATISTICS Example Article « Gerry Christiansen — Thu, 29 Jul 2010 23:35:46 +0000

[...] Click Here « Simulating Oracle ASM Disks [...]

By: Blogroll Report 05/02/2009 – 12/02/2010 « Coskan’s Approach to Oracle

Blogroll Report 05/02/2009 – 12/02/2010 « Coskan’s Approach to Oracle — Wed, 10 Mar 2010 02:28:23 +0000

[...] Kerry Osborne-gather_plan_statistics [...]

By: osborne

osborne — Wed, 03 Mar 2010 17:00:11 +0000

David,

Thanks for the comments. I just updated the post with another script (gps.sql) that just prompts for the SQL_ID and adds the GATHER_PLAN_STATISTICS hint to it (via a Profile). A little more straight forward than the generic create_1_hint_sql_profile.sql script.

Kerry

By: David Mann

David Mann — Wed, 03 Mar 2010 16:25:04 +0000

Incorporating this as a hint is a great idea, never thought of that but it makes sense.

I also like the idea of temporarily messing up stats to make sure they are affecting the XPLAN as expected.

A couple of more tools for my toolbox, thanks!

By: osborne

osborne — Thu, 18 Feb 2010 14:43:44 +0000

Anad, My dplan_allstats.sql script is just DBMS_XPLAN.DISPLAY_CURSOR with the ALLSTATS format option prompting for a sql_id and child_number (like so):

set lines 180
select * from table(dbms_xplan.display_cursor('&sql_id','&child_no','allstats'));

It won't show the A-Rows column unless the statement was instructed to collect the extra information. This can be done by running with the GATHER_PLAN_STATISTICS hint or the session having statistics_level = all, or _rowsource_execution_statistics = true. You should get a note at bottom of the xplan output like so if you have not enabled the collection of the extended statistics.

Note
-----
   - Warning: basic plan statistics not available. These are only collected when:
       * hint 'gather_plan_statistics' is used for the statement or
       * parameter 'statistics_level' is set to 'ALL', at session or system level

Hope that helps. Kerry

By: Anand

Anand — Thu, 18 Feb 2010 07:33:21 +0000

Hi Kerry,
When i am generating the explian plan using DBMS_XPLAN.DISPLAY_CURSOR with format “ALLSTATS LAST” i am not getting the A-rows,A-time etc columns?Why is it so?What all i am getting is “OMem | 1Mem | Used-Mem | Used-Tm”

Regards,
Anand

By: Anand

Anand — Thu, 18 Feb 2010 07:09:20 +0000

Hi,

Nice post, very informative.Where can i get dplan_allstats script?

Anand