Database high availability (Best solution in this sceneio)

Question

Dear All,
We have 2 database servers, in 2 different continents. Operating system is Linux and Oracle 11gR1 is the database. Connectivity among the servers is over the internet.
There are many possible ways to provide high availability of data to applications that are connected to both database. Obviously people near to the server will be accessing data from their nearest server to improve performance of the applications as applications connecting database will also be on server nearest to their geographical location.
However inserts, updates and deletes functions should be online and changes must reflect to the users accessing any database server.
There are several ways to achieve this objectives, like oracle streams, oracle data guard and also there are several options available within these main categories.
I want to find out the best possible way to perform this functionality. Please guide and help me in this.
You can ask me any question you want that can help to understand the scenario. The main concern is the performance of database servers.
Thanks, Imran

Answer 1

As i read the whole thread there is always require you need absolute current data on both end, non of them can be far away or behind to each other, the solution you are proposing yourself to replicate the data itself require more bandwidth between these two node, not only require more bandwidth but require constant traffic on both end, if you go with data guard then there is one way traffic , you cannot go tro and far , as far as concern about multi master replication then ask yourself how much the data change rate will imply to identify network overhead between them, what would you do if network goes down between both node? it would be like pulling yours hair if any complexity occurs between two node like constant updating the same data at both node.
As you said
First: All the entries are stored in one database i.e. the primary database, and using some method these records are also transfered to the other database. However the queries and reporting should be done from local database as per user's/application's geographical location.+
Second: Entries are records locally and immediately replicated to other database, as the employee table we have has employee_id the primary key and this has to be always unique. There are many other tables like this. reporting and query will obviously from the local database.+
From above two point there is confusion with yours first point . You cannot ignore current data availability at both end due to application integrity like (primary key , foreign key etc) otherwise alter yours application with unique site key "PK","UK" within yours all application primary key and foreign key.I am not much aware about replication but i am sure you cannot handle real time data availability at both end, there is always some delay at both end.
If you ask my opinion then i would go one centralized location for yours scenario irrespective the geographical disbursement cause there are applications that have already seen over the net which access the centralized location from too far from the centralized server i.e yahoo server, google server and many more.There are various dedicated submarine optical fiber cable link exist there , you need to contact yours regional vendors like wateen,PTCL etc for such fibre link.
Khurram