Unix Backup and Recovery

Database Structure

There are many terms thrown around when one is discussing RDBMSs. The good news is that you don’t need to know all of them to properly back up and recover databases. You do need to know some of them, though—about 20 individual terms. It’s helpful to know:

• What all the different storage elements are and what they are called

• How these elements are logically organized within the RDBMS

• What facilities are in place to protect and back up the data

This information can be complex, because it depends a lot on how you look at the data. This chapter presents this information from first a power user’s, then a DBA’s, point of view. The various building blocks of a database are defined, although we may have to go up and down the building a bit before we’re done!

The Power User’s View: Logical Elements of a Database

Before looking at how databases are stored on disk, let’s look at the “user’s” view of a database. This is necessary since some of these terms are used in the definition of the storage elements. It might be more appropriate to call this a "power user’s view,” since many users will have little or no knowledge of any of these terms. But unless they want to start doing the DBA’s job of putting a database together, these terms may be all that they would ever need. The terms are presented in no particular order, since it is very difficult to define one term without using another one. Therefore, it may help some readers to read this section more than once.

This view also ...