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The customary configuration of a Yii application includes just a single database section in the protected/config/main.php file, but it's easy to extend this to support more than one, tying each Model to one of the databases.
Relational databases do not support inheritance so if we need to represent it, we have to somehow store meta info while keeping performance by minimizing JOINs. One way to solve this problem is using single table inheritance. All fields for the whole class tree are stored in a single table. Class name is stored in the type field of the same table.
One of the common tasks the web application might be required to perform, especially the app using some kind of a CMS, is to save the history of data changes. Your client for sure will want the answer to this simple question - If I mess this up or delete by accident can we bring it back? Well, DB backup is one thing and quick recovery is another - let's talk about latter one.
I like programing on my localhost, however it really bugged me to make changes to index.php & config files on my production server. After combining all available wiki articles on this topic and some trial and error this is what I use for my applications so I could just upload it to production server and it will work without any changes.