Re: Sequence Generation and Replication

In article <20000517014126.18544.00003223_at_ng-fo1.aol.com>,   sqljames_at_aol.com (Sqljames) wrote:
> I was wondering if there was a way to replication sequences when your
 are using
> a multi-master Advanced Replication model.
>
> Thank You In Advance,
>
> James
>

No, its not possible. The problem is that the sequences would end up generating dups *unless you replicate them in real time* which would sort of obviate the advantage of async replication.

The solution is:

o determine the maximum number of sites you'll have in your replicated database (say its 100 for example).

o multiply that by 10 for good luck (so we have 1000 now).

o at site1, create sequence my_seq start with 1 increment by 1000;   at site2, create sequence my_seq start with 2 increment by 1000;   ...
  at siteN, create sequence my_seq start with N increment by 1000;

Now you have unique sequences that don't need to be replicated, are very fast (and you have the nice side effect that a simple MOD() on the generated number can tell you the site a row was created on)

--
Thomas Kyte                              tkyte_at_us.oracle.com
Oracle Service Industries
http://osi.oracle.com/~tkyte/index.html
--
Opinions are mine and do not necessarily reflect those of Oracle Corp


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