Re: One way replication in multimaster environment

Very interesting question.

Couple years ago, I had very similar problem: I had one "central" database, which had to consolidate data from multiple "source" databases (having identical schemas) in "real time" with as little delay as possible after transaction occurs on the "source" database, and at the same time "source" databases should not be getting data from their piers (or from "central" database). I looked at the "advanced multimaster replication" (offered by Oracle) and didn't find a way to use it as a solution to my problem.

I ended up designing my "own" replication process and writing code (triggers and queue for replicated data on the "source databases" and stored procedures and replicating job on the "central" database) to support it. Of course, this solution means, that I have to modify replication code (triggers and stored procedures) every time, when there are changes to the database schema (but this does not happen very often), and my solution does not replicate DDL. So, when new release of our product comes out, it includes necessary code to modify "source" and "central" database schemas and "replication" code appropriately.
So far, so good: this solution works reliably on multiple installations. Forgot to mention also, that it accounts also for the time intervals, when network between "source" and "destination" databases is down, or database on any side of replication is down: "replicated data queue" on the "source" databases takes care of these problems. Also, "conflict resolution" is taken care of by assigning "source_id" (which is part of PK on each of replicated table) to every replicated record. Also, process of setting up my replication is very simple (it's automated with the scripts, I wrote), so our field engineers are doing it on customer sites without having any knowledge about databases.

So, I'd love to see, if someone has a solution, which utilizes replication provided by Oracle, to this pretty "common" (in my mind, anyway) problem.

Igor Neyman, OCP DBA
ineyman_at_perceptron.com

• Original Message ----- To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com> Sent: Friday, May 03, 2002 12:18 AM

> hi experts,
>
> In my replicated environment, i have one site (example: site X) that
> consolidate data from other sites (example : site Y and Z).
>
> I'm using multimaster to push transaction from site Y and Z to site X.
> How can i set - off the replication in site X , cause i dont want site X
to
> push the changes to other sites or to disable row-level replication.
>
> any idea ?
>
> Thanks
>
>

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Author: Igor Neyman
  INET: ineyman_at_perceptron.com

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