Вопрос об архитектуре SaaS от новичка

Good questions.

One thing that comes to mind is that if you have multiple databases which you roll out in a staged manner to reduce the likelihood of breaking all of your customers, you will have to address the issue of what to do if the db structure changes. You will either have to be very rigorous with respect to maintaining backward compatibility, or else deploy separate versions of your code base and somehow manage which tenants are associated with which databases.

We are providing our application using a SaaS model as well.

It was, initially a Windows app which worked similar to your multiple database proposal. Upon login, the win app would authenticate against a single "licensee" database which would then respond with connection information for a database specific to that licensee. The nice thing about this was that it provided 1) physical separation of licensee data, which our customers liked and 2) enabled us to physically locate the database on a server geographically closer to the users which both improves performance and avoids some potentially tricky legal and regulatory issues with respect to providing data across country boundaries.

Of course, since the app was a thick client app, we could get away with making database changes and pushing them out to one licensee at a time. When we were ready to upgrade, we could push out an updated thick client in conjunction with the new database - thereby ensuring that the codebase was a match with the database. As long as the common "licensee" authentication database stayed consistent, this worked fairly well.

On the other hand, though, this solution brought with it all of the problems of maintaining and managing a thick client approach which finally lead us down the thing client, browser-based approach.

In our new model, everything is in a single database. When we have updates, we push both the code and the db out at the same time. This solves the problem of keeping the code base consistent with the database structure. However, we are now confronted with the issues mentioned in #s 1 and 2, above, which we have yet to resolve.

I hope this provides some food for thought for you.

I, too, am interested in this question.

Thanks for the post.

-S