RE: HOW TO SET SEQUENCE VALUE
- From: "Taylor, Chris David" <ChrisDavid.Taylor@xxxxxxxxxxxxxxx>
- To: 'Howard Latham' <howard.latham@xxxxxxxxx>
- Date: Thu, 29 Mar 2012 07:49:45 -0500
Howard,
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?
Thanks,
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: Howard Latham [mailto:howard.latham@xxxxxxxxx]
Sent: Thursday, March 29, 2012 7:44 AM
To: Taylor, Chris David
Cc: ilmar.kerm@xxxxxxxxx; 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@xxxxxxxxxxxxxxx>
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
> checked)
>
>
>
> 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@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 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.
>
> Ilmar
>
> --
> //www.freelists.org/webpage/oracle-l
>
>
--
Howard A. Latham
--
//www.freelists.org/webpage/oracle-l
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