Re: CR Block copies, always 6 in 10.2.0.3?

From: "LS Cheng" <exriscer@xxxxxxxxx>
To: ax.mount@xxxxxxxxx
Date: Mon, 24 Mar 2008 13:00:53 +0100

I am not sure how this works but for example in  Grid Control repository
sometimes I see 400 CR copies for an unique index!


--
LSC


On Mon, Mar 24, 2008 at 1:10 AM, amonte <ax.mount@xxxxxxxxx> wrote:

> Hi all
>
> I read from somewhere, I think the wait interface book where it states
> that the number of clone copies of data block is governed by
> _DB_BLOCK_MAX_CR_DBA which is set to 6. If there will be more than 6 copies
> then Oracle will wait for the buffer, this is what I dont get, wait?
>
> So I fired up 7 sessions and see what kind of wait is this! I updated the
> same table (EMP from scott tiger), 14 rows in same data block and each
> session updates a row, then each session fires a query agaisnt EMP. I
> noticed that the number of CR is never more than 6 despite having 7 updates
> concurrently and I dont see what is really going on. Does this mean whenever
> the 7th CR block is being cloned one of 6 previous CR is being overwritten
> or "destroyed"?
>
> I did the test in 10.2.0.3.
>
> TIA
>
> Alex
>
>
>

References:
- CR Block copies, always 6 in 10.2.0.3?
  - From: amonte

Re: CR Block copies, always 6 in 10.2.0.3?

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