I am a Freelance Web Developer but not a Database Administrator at all except basic Database Operations like DML etc. Today I got a client asking me to develop a Web based application but there is a Problems concerning Databases and I don't know what strategy would best suit.
My Client got 6 different MS SQL and Oracle databases and all these databases are frequently updated with 3 to 4 seconds each updated with 6 different applications. Now I have to develop a web based single application to show data from all these 6 different databases.
My Problem is that what strategy should I choose for my web based application specially when it's about performance
1) Replicate Database from all these 6 different databases into single MySQL database keeping in mind that these are updated every 3 to 4th second?
2) Or my application should directly access these 6 databases?
My Client says that my web application will be generating many different graphs which sometimes can take 30 seconds to generate single graph.
I would request my honor DBAs that please suggest me what would best suit for my application? My client doesn't want that his current 6 databases get slow down or unresponsive when application is accessing to generate graphs or something like that. Client is willing to let me make my choice to choose from above options. Web application should show the most recent data from database so if I choose to replicate then I will have to replicate every 3rd second.
Please kindly also tell that is it possible to tell database to replicate new data to other database every 3rd second and if yes then will it be resource intensive specially when 6 different database will do the same on single database?