I'm new to Oracle.
My leader asked me to find way to duplicate oracle database between two different oracle sites.
It need to be online and differential backup.
The only way i know is to use the "exp","imp" utils to do it but it's not effective.
there are several ways to do such duplications:
* exp/imp (as you mentioned)
* database links with self-written data integrity triggers
* multi master replication
* standby databases
(and I'm sure there are several more)
each if them has their own advantages and disadvantages. A deep analysis of your needs and the technical possiblities is necessary.
Nevertheless, a snapshot might be helpful.
Two priority questions:
1. Must your two databases be open for read/write operations at the same time?
2. Must the data in your two databases be syncrhonized?
If the answer to both questions is "yes" then consider Oracle Advanced Replication in Oracle9i, or Streams in 10g. You could also use EMC's SRDF, if you have EMC storage arrays. You could also use Quest's SharePlex or DataMirror's iReflect.
If the answer to the first question is "no" but the answer to the second question is "yes", the consider Oracle Standby Database with Data Guard. Alternatively, Quest's SharePlex or DataMirror's iReflect could also be used here.
If the answer to both questions is "no" then consider imp/exp. Atlernatively, many of the backup/recovery software programs like Oracle RMAN give you the ability to duplicate a database at a remote location.
Thanks for your kind help.
But I still have some guestions.
For your each point , is there any on-line document to reference? I need the information more detail. Thank you.
In my scenario,I need to synchronize some of the user tables like "users","organizations" between two oracle sites with the same user schema.
For your opinions ,it sounds that I need third-party tools to do the replication. Is that true?
there is a lot of free available documentation on OTN  (free registration necessary),
especially white papers and the full documentation.
There are also several 3rd party products available, but also the products sold by oracle are powerful. It depends on your needs which one fits them best. (You havn't answered any questions above according your requirenments)
Do you mean the two priority questions by markrem?
In my scenario(replied in #5),I think the first question is "no" but the answer to the second question is "yes".
Ok I repeat my scenario again and more detail:
My company needs to construct an environment with two Oracle sites for PDM(Product Data Management) system. Both two sites with the same user schema (same table structure) but each site creates its own data. Some data like "user account","organization","salary information","reference information" need to be synchronized between two sites to meet the requirement of central control. The synchronization must be bi-direction.
The "Oracle Standby Database with Data Guard" solution needs a "standby database". Does it mean that one Oracle site is primary and the other site is standby ? But it sounds that you can't access any data in standby db, because the db in recovery mode?
I'm familiar with SQL Server but Oracle. This is a quite hard task for me beacause the complication of Oracle and lack of resources(money). ^^
just to make sure:
you have 2 databases, both with the same user and tables.
Both are used at the same time from 2 seperated applications, but need to provide all data written/modified to all databases?
If this is correct I'd point towards MultiMaster replication or RealApplicationCluster.
both have different requirenments and advantages.
i don't know of any 'free' ways to do so.
but I believe the MultiMasterReplication is part of Oracle Enterprise Edition (please check this with your Oracle Sales Representant) and so no additional fee is needed.
Nevertheless, don't forget about training costs or just the time you'll need to get used to _any_ solution.