Re: Oracle MAA and active-active replciation between site

  • From: "LS Cheng" <exriscer@xxxxxxxxx>
  • To: Pradeep.Chetal@xxxxxxxxxxxxxx
  • Date: Tue, 12 Aug 2008 08:47:11 +0200

Just use Data Guard and dont complicate your life with replications!


Thanks
--
LSC

On Mon, Aug 11, 2008 at 10:29 PM, Pradeep Chetal <
Pradeep.Chetal@xxxxxxxxxxxxxx> wrote:

>
> Yavor,
>
> If we are OK with few hours of delay between the 2 sites, is there other
> software that works to keep the 2 sites in sync?
>
> Some folks I talk to, do NOT like Oracle Advanced Replicatiom.
>
> What about Golden Gate software or IBM's Data mirror?
>
> -- Pradeep
>
> -----Original Message-----
> From: Yavor Ivanov [mailto:Yavor_Ivanov@xxxxxxxx]
> Sent: Friday, August 01, 2008 6:57 AM
> To: Pradeep Chetal
> Cc: oracle-l@xxxxxxxxxxxxx
> Subject: RE: Oracle MAA and active-active replciation between site
>
>
>        The big concern about the application in replication environment
> are the conflicts.
>        - You should in all ways avoid updating or deleting the same row
> of a table from both sites at the same time.
>        - The same for the inserts. Your application should not be able
> to insert rows with the same primary key values from both sites. E.g. if
> you have primary keys generated by sequence, one of the sites should
> start with 1 increment by 5 and the other will start with 2, increment
> with 5.
>        - You must have primary key on all tables. This is not mandatory
> from the docs, but it is always good practice, even without replication.
>        - You should design all triggers carefully - when there is an
> insert in a table on one site, the trigger may make some things like
> inserting/updating/deleting on other tables. Then when this is
> replicated to the other site, there will be insert again, but the
> trigger should not fire again.
>        - When there is a conflict, a whole transaction is not
> replicated. Even if you do not care for this problematic row in this
> table, a conflict on a row of a table will block the whole transaction
> and you have to resolve it.
>        - If you decide to let the replication of all following
> transactions be done in spite of the conflicts, you may have lots of
> anomalies in the data. In the other hand, resolving a conflict may take
> some time and you may not want to block the whole replication because of
> a single problematic transaction
>
> Regards,
> Yavor Ivanov
> Oracle Certified Master
>
>
> -----Original Message-----
> From: Pradeep Chetal [mailto:Pradeep.Chetal@xxxxxxxxxxxxxx]
> Sent: Friday, August 01, 2008 12:56 PM
> To: Yavor Ivanov
> Subject: RE: Oracle MAA and active-active replciation between site
>
>
> Yavor,
>
> In terms of wise application design, what do you recommend?
>
> What are the big 3-4 things we should worry about?
>
> -- Pradeep
>
> -----Original Message-----
> From: oracle-l-bounce@xxxxxxxxxxxxx
> [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Yavor Ivanov
> Sent: Friday, August 01, 2008 3:05 AM
> To: Pradeep Chetal; oracle-l@xxxxxxxxxxxxx
> Subject: RE: Oracle MAA and active-active replciation between site
>
>
>        I've done one project active-active replication using oracle's
> Advanced replication. There is good documentation about this.
>        There are 2 basic problems with this
>                - The conflicts. You will always have conflicts on
> active-active replication. Most of them can be avoided by wise
> application and process design, but it will need lot of thinking. And
> you will still have conflicts you cannot avoid and cannot resolve
> automatically
>                - The burden. It is much harder for administration.
> Adding a simple column is pain in the ass, Yes, there are procedures,
> but still... It is hard.
>        But it really works - for 2 years now. I would consider this.
>
>        I also have done it with "Basic replication", master -
> (updateable) mvews with 12 active sites across the country (one master
> in HQ). But it is even harder to support this than Advanced replication.
> And the application on this project was specially built with the
> replication in mind. It works for 9 years now (we started it on 8.1.5,
> now all the servers are 10.2). But I would never advise this approach,
> this is aged and arcane thing.
>
> Regards,
> Yavor Ivanov
> Oracle Certified Master
>
> -----Original Message-----
> From: oracle-l-bounce@xxxxxxxxxxxxx
> [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Pradeep Chetal
> Sent: Thursday, July 31, 2008 6:18 PM
> To: oracle-l@xxxxxxxxxxxxx
> Cc: Pradeep Chetal
> Subject: Oracle MAA and active-active replciation between site
> Importance: High
>
>
>
> Hi,
>
> Oracle has an MAA with
>
> http://www.oracle.com/technology/deploy/availability/pdf/MAA_WP_10gR2_Ro
> admap.pdf<http://www.oracle.com/technology/deploy/availability/pdf/MAA_WP_10gR2_Roadmap.pdf>
>
> However, one of our clients would like to have active-active replication
> between remote sites, so that each site can be used.
>
> Have you done this? What software did you use?
>
> Also, what are the limitations on schema, if any to do this?
>
> Thanks in advance,
>
> -- Pradeep
>
>
>
>
> Pradeep Chetal
> Sr. Director - Infrastructure Architecture
>
>
>
> Mformation Technologies Inc.
> Switchboard: +1 732 692 6200
>
>
>
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>
>
>
> Visit WWW.MFORMATION.COM and see how the MFORMATION SERVICE MANAGER can
> help you to transform your business
>
>
> Please consider the environment before printing
>
>
>
> Visit WWW.MFORMATION.COM and see how the MFORMATION SERVICE MANAGER can
> help you to transform your business
>
>
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