I am new at database design, and my question relates to the trade-offs between putting all data in one database or several for mysql. For example, say I have an application where a users login from their mobile phones and read/write data to a database. Say there are roughly 10-15 tables in the database and each user will add approximately 20,000 records per year. Each user should not have access to data from another user. Users have to register in some way to create their database in the first place. When does it make sense to give each user their own database versus putting all the data into one database (ie one set of tables) and with multiple userIDs? 10 users? 1,000 users? Never?
Thanks! Mark
