Re: Pinning Objects
Date: Mon, 20 Jul 2009 11:08:57 -0700 (PDT)
Message-ID: <72b9287d-c493-4f15-8cf7-342a78b97cc2_at_f20g2000prn.googlegroups.com>
On Jul 20, 9:57 am, The Magnet <a..._at_unsu.com> wrote:
> Hi,
>
> We want to pin a couple of tables, hoping to increase some
> performance. From the docs, a pinned table means less reads from
> disk, etc.
>
> If the table gets updated or inserted into, is there any advantage to
> this? If yes, how does the committed transactions get saved?
If you just let Oracle do its thing, blocks that get used a lot will stay in memory, since Oracle uses an LRU algorithm. Also, small tables use a different algorithm for full scanning ("The definition of a small table is the maximum of 2% of the buffer cache and 20, whichever is bigger.") I used to have noticeable results on certain objects with a recycle pool, but nowadays don't seem to need to bother. Be careful about catching obsessive tuning disorder. Take any rule of thumb that uses percentages with a very large dose of salt. Remember that most performance problems come from the app code. "Hoping" is not a particularly good tuning methodology. You want to use a methodology that tells you how to find what is wrong and where to put your effort.
See metalink Note: 135223.1 and note the auto-tuning part. And keep a lot of salt handy.
See commit transactions in the concepts manual for the basic idea on how that works.
Do you have an actual problem to solve? You need to state it exactly. http://dbaoracle.net/readme-cdos.htm
jg
-- _at_home.com is bogus. http://www3.signonsandiego.com/stories/2009/jul/20/1m20judges23536-federal-agencys-sd-spat-revealed/?uniontribReceived on Mon Jul 20 2009 - 13:08:57 CDT