6) Database migration
The task database migration is about how to transfer the complete contents of a database between two separate physical servers and have different versions of the same database. For example, migrating a database from one SQL Server 2005 to SQL Server 2008 or migrating a database from MySQL 5.4 to MySQL 5.5.
Migration between different versions of the database is generally not an easy task. In addition to considering the specific changes for each version you need to transfer objects, data, database settings, server permissions, users, directory structures, jobs, and other resources. The migration is more complex on databases that have versions not as frequent as SQL Server and Oracle because in these cases the differences in functionality between the databases’ versions tend to be higher, despite the concern of manufacturers with backwards compatibility. Both SQL Server and Oracle provide wizards for migration. MySQL and PostgreSQL often suggest the transfer of files (both data and configuration) as the most viable alternative for migration, except in specific cases where the database engine has been modified. A comparison of the level of difficulty to the task Database migration is presented in Table 1.
Table 1. Comparison of the level of difficulty to the task Database migration.
The task Security is about how the DBA create security objects and work with groups that allow access to management of user accounts.
All databases allow the use of DCL (Data Control Language) commands such as GRANT, DENY, and REVOKE. These commands are used to indicate whether or not a user has access permission to the object. Furthermore, the four databases have also ways to group the users (called roles) in order to facilitate the assignment of group permissions. However, SQL Server has some peculiarities regarding the types of roles (server role or fixed database role), more granular permissions as a column of a table and user accounts authenticated by Windows and not the database. A comparison of the level of difficulty to the task Security is presented in Table 2.
Table 2. Comparison of the level of difficulty to the task Security.
In the next part, we will analyze about Audit and Task Scheduling.