I plan to create a websystem where organisations (customers) can setup a website with particular functions and their information stored in a (mysql) database. I already started with a database design which includes one master database plus a customer database for each new organisation (which is created after filling in a webform).
Now I start to question my database design decision and wonder whether just single database for all organisations would not be a better choice ? The reason being that there will be various communication (==information exchange) between some of these organisations and these communicating organisations would have unnecessary copies of some tables (e.g., they both have 2-3 tables which are almost copies of each other and therefore they could also share).
Furthermore, implementing the information exchange seems a bit more complex with various databases than with one database. On the other hand, I assume(d) that database queries by the various customers within a single very large database may require much more time than with a system with multiple databases.
Bottomline, as a non-database expert I'm not sure which of the two options would be best to proceed with, and therefore would appreciate your advice.