Re: Understanding Gets, Pins and Reloads - V$librarycache

I was reading the link.

It is advising the use of cache hit ratios to measure the effectiveness of the shared pool. An example calculates the hit ratio to be 99.9%. Also the following:

"Lastly, a broad indicator of library cache health is the library cache hit ratio. This value should be considered along with the other statistics discussed in this section and other data, such as the rate of hard parsing and whether there is any shared pool or library cache latch contention"

I take it using cache hit ratios are not all that evil?

On 5/9/07, Don Seiler <don_at_seiler.us> wrote:
>
> See the Database Performance Tuning Guide on the shared pool:
>
>
> http://download-east.oracle.com/docs/cd/B19306_01/server.102/b14211/memory.htm#i52830
>
> Does a pretty good job of describing V$LIBRARYCACHE and how to use the
> info within.
>
> Don.
>
> On 5/9/07, Thotangare, Ajay (GTI) <Ajay_Thotangare_at_ml.com> wrote:
> >
> >
> >
> >
> >
> > Can someone please explain in detail the gets, pins and reloads in
> > v$librarycache.
> >
> > How are these columns related to each other? When would gets, pins and
> > reloads increase?
> >
> >
> >
> > I read some definitions like
> >
> > The GETS column indicates the number of times, since database instance
> > startup, that the
> >
> > System requests handles to library objects in this namespace.
> >
> >
> >
> > The PINS column indicates the number of times, since database instance
> > startup, that the
> >
> > System issues pin requests in order to access objects in the cache.
> >
> >
> >
> > Will both not go 1:1 ratio?
> >
> >
> >
> >
> >
> >
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> --
> Don Seiler
> oracle blog: http://ora.seiler.us
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