Re: db buffer cache advisory clarification

From: Stephen Anderson <st.anderson_at_gmail.com>
Date: Wed, 29 Mar 2006 10:27:36 +0100
Message-ID: <a9a8b6c0603290127p4b4873bava8fb1d5ce55a309b@mail.gmail.com>

Hello,

Ran a 7 minute snap this morning - results are getting worse! Physical Reads are at 6278/s and Logical Reads are 70,844/s.

Buffer Pool Advisory for DB: MERLIN Instance: MERLIN End Snap: 31 -> Only rows with estimated physical reads >0 are displayed -> ordered by Block Size, Buffers For Estimate

        Size for  Size      Buffers for  Est Physical          Estimated
P   Estimate (M) Factr         Estimate   Read Factor     Physical Reads
--- ------------ ----- ---------------- ------------- ------------------
D             16    .3            1,985          0.07        124,118,645
D             32    .5            3,970          0.04         70,906,440
D             48    .8            5,955          0.02         29,259,452
D             64   1.0            7,940          1.00      1,783,067,416
D             80   1.3            9,925          0.99      1,757,988,089
...
D            256   4.0           31,760          0.85      1,523,232,446
D            272   4.3           33,745          0.85      1,507,672,223

Now we can see over 1 billion PIO's, so it cannot be a formatting thing. The metalink note that Jared suggested merely chose to format it differently.

On 3/28/06, jungwolf <spatenau_at_gmail.com> wrote:
>
> Stephen,
>
> This is for a 15 minute snapshot? It seems a little strange to me.
> > Size for Size Buffers for Est Physical Estimated
> > P Estimate (M) Factr Estimate Read Factor Physical Reads
> > --- ------------ ----- ---------------- ------------- ------------------
> > D 64 1.0 7,940 1.00 937,436,311
>
> 937436311/(15*60)=1041595.9 or over 1 million physical reads per second.
>
> Maybe something else is going on?
>
> Steven

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Received on Wed Mar 29 2006 - 03:27:36 CST