Re: Money for nothing and ASH for free
- From: "John Kanagaraj" <john.kanagaraj@xxxxxxxxx>
- To: kylelf@xxxxxxxxx
- Date: Thu, 21 Jun 2007 09:56:12 -0700
Thanks Kyle. I know you advocated Direct SGA access for the same data,
but this is different, correct?
I have the issue of having to manage older 8i/9i databases so I
adapted 10g's ASH and Metrics ideas in a slightly different way and
wrote some code that could be used as the basis of a 'backport' of
these tools. Actually presented these ideas as a paper at COLLAB 06
and OOW 06, but stopped there and did not actually develop that into a
tool (I just display/spool the simulated ASH output and interpret it
as I see it). Let me know if you would like to see that paper. You can
probably use that to expand this concept to ADDM....
John
On 6/20/07, kyle Hailey <kylelf@xxxxxxxxx> wrote:
If you are on 10g and already have the performance pack, you can probably
skip this email.
Some people have been complaining about the licensing of the performance
packs. I agree it's weird that v$active_session_history is there but you
aren't suppose to query it. On the other hand I think the performance pack
is definitely worth it if you are working on an important database where
slowdowns or outages have financial impact.
On the other hand, if you don't want to pay, can't pay or if you are on
version 7, 8 or 9 then you can simulate ASH.
I've put together a plsql package that simulates ASH on
http://www.perfvision.com/ash.php
Active Session History is an amazingly rich sort of peformance data and half
the fun is just thinking of new ways to mine the data.
Things you can do are graph system load over time, find the longest running
SQL, find the top SQL by cpu or wait, or see the resource breakdown for a
single SQL etc etc
This paper explains a bit of ASH power
http://www.perfvision.com/papers/Sampling.pdf
Examples of some SQL and output from querying ASH data are on
http://www.perfvision.com/sql/ash/note.html
One cool thing is, even if you are on 10g, the queries from the simulated
ASH should be roughly compatible with v$active_session_history since it's
basically the same structure and columns. There are a few differences
though.
Best Wishes
Kyle Hailey
http://perfvision.com
--
John Kanagaraj <><
DB Soft Inc
Phone: 408-970-7002 (W)
** The opinions and facts contained in this message are entirely mine
and do not reflect those of my employer or customers **
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