Re: HOW TO SET SEQUENCE VALUE
- From: TESTAJ3@xxxxxxxxxxxxxx
- To: howard.latham@xxxxxxxxx
- Date: Thu, 29 Mar 2012 09:03:13 -0400
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The numbers even cached ones are ONLY lost in the event the instance is=20
aborted(either by shutdown abort or dumping). when a shutdown immediate=20
is run, the last number not used is pushed back out so when it comes back=20
up, you would lose none.
As stated by others don't expect continuous numbers, as also a select from =
the sequence and a rollback will lost numbers also.
joe
From:
Howard Latham <howard.latham@xxxxxxxxx>
To:
ChrisDavid.Taylor@xxxxxxxxxxxxxxx
Cc:
"ilmar.kerm@xxxxxxxxx" <ilmar.kerm@xxxxxxxxx>, Oracle-L Freelists=20
<oracle-l@xxxxxxxxxxxxx>
Date:
03/29/2012 08:45 AM
Subject:
Re: HOW TO SET SEQUENCE VALUE
Sent by:
oracle-l-bounce@xxxxxxxxxxxxx
Beware sequence number can be lost even with nocache. You cannot use
them as a contiguous numbering system where missing numbers will cause
questions. Best rule of thumb don't use them if someone will look at
them.
On 29 March 2012 13:27, Taylor, Chris David
<ChrisDavid.Taylor@xxxxxxxxxxxxxxx> wrote:
> Also be advised that sequences can age out of the cache and lose your=20
cached values. The next time the sequence is called a new cache of=20
numbers is generated and the unused sequence values [before it was aged=20
out] are 'lost'.
> (I wanted to verify that info was correct before I posted so I double=20
checked)
>
>
>
> Chris Taylor
>
> ?Quality is never an accident; it is always the result of intelligent=20
effort.?
> -- John Ruskin (English Writer 1819-1900)
>
> Any views and/or opinions expressed herein are my own and do not=20
necessarily reflect the views of Ingram Industries, its affiliates, its=20
subsidiaries or its employees.
>
>
> -----Original Message-----
> From: oracle-l-bounce@xxxxxxxxxxxxx [
mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Ilmar Kerm
> Sent: Thursday, March 29, 2012 7:01 AM
> To: Oracle-L Freelists
> Subject: Re: HOW TO SET SEQUENCE VALUE
>
> Quite dangerous advice, I think... Cache is a very important part of=20
sequence performance (and maybe the default 20 is too low nowadays also).=20
Using NOCACHE should be a very rare occasion, when "losing"
> sequence numbers on instance restarts is not allowed.
> USER=5FSEQUENCES just reports what value is stored in data dictionary, bu=
t=20
database instance is giving out cached sequence numbers. So the difference =
is normal.
>
> Ilmar
>
> --
> //www.freelists.org/webpage/oracle-l
>
>
--=20
Howard A. Latham
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