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icon5.gif  Replication between 4 nodes [message #128336] Mon, 18 July 2005 01:12 Go to next message
Achchan
Messages: 86
Registered: June 2005
Member
Hi all,
I want to synchronize a master database with content of 3 other databases.In other word,Changed data should take effect in master database in online manner.All databases are in a LAN or high speed DSL.
I first decided to do this using some triggers on 3 databases tables with proper database link to master one.
But somebody told me the best way is Replication.I have no replication experience.Is that the proper way in your opinion?
Where should I find some resource about this topic?
-Best wishes
Re: Replication between 4 nodes [message #128413 is a reply to message #128336] Mon, 18 July 2005 07:36 Go to previous messageGo to next message
smartin
Messages: 1803
Registered: March 2005
Location: Jacksonville, Florida
Senior Member
First, make sure you really want to do replication before you actually do it. If all 4 nodes are on one LAN, why is it you have 4 separate databases instead of one database, possibly with RAC? Also oracle has some other options like standby databases (logical and physical), streams, and change data capture, in addition to replication, which may solve your need depending on what exactly your need is.

There is documentation on all of these options, usually just reading chapter one of each guide will give you a good enough idea about each choice to determine if you should pursue further.

But the big question to answer is, why have 4 separate databases which need to be kept in synch in the first place?
Re: Replication between 4 nodes [message #128487 is a reply to message #128413] Mon, 18 July 2005 23:11 Go to previous messageGo to next message
Achchan
Messages: 86
Registered: June 2005
Member
That is just a demo version of our solution!
In fact there will be 10-15 databases in different places and ONE master database that will reside in Management department and want to manage,report,....
Furthermore 10-15 databases do logically the same business in multiple sites and their work is related to each other so should be aware of each others data.(At worst with a 1 hour latency and at best instantly).
Thanks
Re: Replication between 4 nodes [message #128627 is a reply to message #128487] Tue, 19 July 2005 19:42 Go to previous messageGo to next message
andrew again
Messages: 2577
Registered: March 2000
Senior Member
Using replication (snapshots/materialised veiws) can definitely do this and it's very simple to implement. The technology has been around for a long time and is reliable. The implementation details have changed over time. Snaphot=materialized view. Check on Metalink.oracle.com for consise examples or see the documentation on otn.oracle.com

Whenever you have replicated data you need to consider how to get the databses back in sync if one is recovered to an earlier time, or what cleanup to do if you drop one of the MVs. As smartin says - make sure you look at other methods (like DB links and synonyms) too.
Re: Replication between 4 nodes [message #129320 is a reply to message #128336] Sun, 24 July 2005 00:02 Go to previous messageGo to next message
Achchan
Messages: 86
Registered: June 2005
Member
Thanks for your replies,
I choose Replication using materialized views in Oracle.But now the question is: Can I do that without need to change the application and underlying tables? I know I should create materialized views in multiple sites so shuld I change all tables in those sites with these new materialized views.I mean CTAS the MVs and then drop the original tables?
Thanks for your help.
Re: Replication between 4 nodes [message #129349 is a reply to message #129320] Sun, 24 July 2005 14:23 Go to previous messageGo to next message
andrew again
Messages: 2577
Registered: March 2000
Senior Member
Where does your data change - in your "master" database - or the 3 other ones? In Oracle's terminology, the master database is the one where the data changes (you can have master-slave or master-master) and is replicated to the slave. A master-master allows changes to be made in both ends.

In the master-slave case, the MV is on the slave side, the MV logs are on the Master side.

There are a few considerations regarding your application and referenial integrity (RI). Chances are that your current remote tables have primary/foreign keys. In general you shouldn't have PK, FK on your remote MV tables, because the contents of those tables are dictated by the master site. If you are sure that you won't have a problem, then of course the PK, FKs can be created. If you are replicating Master/Detail tables, put them in a replication group to ensure that RI is maintained.
Re: Replication between 4 nodes [message #129378 is a reply to message #129349] Sun, 24 July 2005 22:44 Go to previous messageGo to next message
Achchan
Messages: 86
Registered: June 2005
Member
Thanks andrew again,
AFAIK we have two different solutions:Materialized views and other one master-master replication.
I need mv method which has a central master containing mv logs that gathers and integrates data from mv sites and propogates them later.
My data will change in mv sites too.so I should use Updatable mvs,Am I right?Beside data conflict problems I want to know:
Should I "CREATE MATERIALIZED VIEW..." in all mv sites and drop all tables in that site and application will use these mvs or not?
If yes so I see many probable changes in application too.AAh!
-thanks
Re: Replication between 4 nodes [message #135541 is a reply to message #129378] Thu, 01 September 2005 02:13 Go to previous message
lallmanish
Messages: 28
Registered: September 2005
Junior Member
hi anddrew

i have got aconcern so i thought i should ask u here only.
i am to deploy a replication at a remote site on a separate
leased line and on the second nic- i just wanted to know
what configurations are reqd in the primary database server
for the connection on the second nic and a separate leased line
thanks
manish
e:manishlall@mhd.co.om
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