RE: HOW TO SET SEQUENCE VALUE
Date: Thu, 29 Mar 2012 07:49:45 -0500
It seems to me that NOCACHE numbers can only be 'lost' if they are selected but never used by a session?
As the values are not stored in memory, they should not be lost by being aged out or instance restarts - right?
Can you clarify an instance where a NOCACHE sequence number would be lost?
"Quality is never an accident; it is always the result of intelligent effort." -- John Ruskin (English Writer 1819-1900)
Any views and/or opinions expressed herein are my own and do not necessarily reflect the views of Ingram Industries, its affiliates, its subsidiaries or its employees.
From: Howard Latham [mailto:howard.latham_at_gmail.com] Sent: Thursday, March 29, 2012 7:44 AM
To: Taylor, Chris David
Cc: ilmar.kerm_at_gmail.com; Oracle-L Freelists Subject: Re: HOW TO SET SEQUENCE VALUE
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_at_ingrambarge.com> wrote:
> Also be advised that sequences can age out of the cache and lose your cached values. The next time the sequence is called a new cache of numbers is generated and the unused sequence values [before it was aged out] are 'lost'.
> (I wanted to verify that info was correct before I posted so I double
> Chris Taylor
> "Quality is never an accident; it is always the result of intelligent effort."
> -- John Ruskin (English Writer 1819-1900)
> Any views and/or opinions expressed herein are my own and do not necessarily reflect the views of Ingram Industries, its affiliates, its subsidiaries or its employees.
> -----Original Message-----
> From: oracle-l-bounce_at_freelists.org
> [mailto:oracle-l-bounce_at_freelists.org] 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 sequence performance (and maybe the default 20 is too low nowadays also). Using NOCACHE should be a very rare occasion, when "losing"
> sequence numbers on instance restarts is not allowed.
> USER_SEQUENCES just reports what value is stored in data dictionary, but database instance is giving out cached sequence numbers. So the difference is normal.
-- Howard A. Latham -- http://www.freelists.org/webpage/oracle-lReceived on Thu Mar 29 2012 - 07:49:45 CDT