Re: reset the SCN for the database

From: Tony van Lingen <tony_vanlingen_at_technologyonecorp.com>
Date: Thu, 16 Jul 2009 10:50:42 +1000
Message-ID: <4A5E7962.3040805_at_technologyonecorp.com>

That would mean that the SCN is a 6-byte integer, or 48 bits, which makes the max SCN exactly 281,474,976,710,656.

Seems that overcommitting in procedures/apps is bad then.. it could lead to a SCN "reset" before the 500 years are over (on a very fast system).. :)

Goulet, Richard wrote:
> Humm, there is 60 seconds in a minute, 3600 in an hour, 86400 in a
> day, 31,536,000 in a year and 15,768,000,000 in 500 years. So at 16K
> commits per second that makes the largest SCN = 252,288,000,000,000
> which is one heck of a lot of transactions.
>
>
> */Dick Goulet/*//
> Senior Oracle DBA
> PAREXEL International
>
>
>
> ------------------------------------------------------------------------
> *From:* oracle-l-bounce_at_freelists.org
> [mailto:oracle-l-bounce_at_freelists.org] *On Behalf Of *K Gopalakrishnan
> *Sent:* Wednesday, July 15, 2009 2:22 PM
> *To:* TESTAJ3_at_nationwide.com
> *Cc:* hrishys_at_yahoo.co.uk; oracle-l_at_freelists.org;
> oracle-l-bounce_at_freelists.org
> *Subject:* Re: reset the SCN for the database
>
> Joe,
>
> Going by the standard answer, it will take around 500 yeras for you to
> run out of SCN with 16K commits/sec. So there is no way you will run
> of SCNs in (y)our life. Also the SCN structure has an internal
> limitation of increment values. It can not be incremented to
> arbirarily high values. So you can not use the ADJUST_SCN or
> _minimum_giga_scn to reach the limit :)
>
> So technically speaking the first error you may get with currnet
> versions of will be ORA-1513, but you will get umpteenl ORA-1558s as
> all the rollback segments would have dead by that time.
>
> Best Regards,
> K Gopalakrishnan
>
> Oracle Database 10g Real Application Clusters Handbook
> http://www.amazon.com/gp/product/007146509X/
>
> Oracle Wait Interface: A Practical Guide to Performance Diagnostics &
> Tuning
> http://www.amazon.com/exec/obidos/tg/detail/-/007222729X/
>
>
> On Wed, Jul 15, 2009 at 12:13 PM, <TESTAJ3_at_nationwide.com
> <mailto:TESTAJ3_at_nationwide.com>> wrote:
>
>
> A discussion many years ago asked "what happens if you run out of
> SCNs?" Curious minds still want to know or has this already been
> answered.
>
> joe
>
> _______________________________________
> Joe Testa, Oracle Certified Professional
> (Work) 614-677-1668
> (Cell) 614-312-6715
>
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> Dec 11-13, 2009 here in Columbus.
>
>
>
> From: K Gopalakrishnan <kaygopal_at_gmail.com
> <mailto:kaygopal_at_gmail.com>>
> To: hrishys_at_yahoo.co.uk <mailto:hrishys_at_yahoo.co.uk>
> Cc: oracle-l_at_freelists.org <mailto:oracle-l_at_freelists.org>
> Date: 07/15/2009 01:08 PM
> Subject: Re: reset the SCN for the database
> Sent by: oracle-l-bounce_at_freelists.org
> <mailto:oracle-l-bounce_at_freelists.org>
>
>
> ------------------------------------------------------------------------
>
>
>
> Hrishy,
>
> Resetlogs does not reset the SCN. It just resets the LSN (Log
> Sequence Number), thats why it is RESET-LOGS. You can advance SCN
> by ADJUST_SCN event (which goes only forward btw). You may
> consider FLASHBACKS to go back to the past.
>
> -Gopal
>
> On Wed, Jul 15, 2009 at 4:44 AM, hrishy <_hrishys_at_yahoo.co.uk_
> <mailto:hrishys_at_yahoo.co.uk>> wrote:
> Hi
>
> One of my environment makes use of streams and if i do a
> incomplete recovery using resetlogs the SCN would be reset.How do
> change the SCN to make it go back to what it was earlier.
>
>
> regards
> Hrishy
>
>
>
>
>
>
>
>
>
>

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Received on Wed Jul 15 2009 - 19:50:42 CDT