Re: CR Block copies, always 6 in

From: LS Cheng <>
Date: Mon, 24 Mar 2008 13:00:53 +0100
Message-ID: <>

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


On Mon, Mar 24, 2008 at 1:10 AM, amonte <> 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
> Alex
Received on Mon Mar 24 2008 - 07:00:53 CDT

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