About Oracle Database

Oracle Database is a relational database with object and Extensible Markup Language (XML) capabilities. In a relational database, all data is stored in two-dimensional tables that are composed of rows and columns. Oracle Database enables you to store data, update it, and efficiently retrieve it, with a high degree of performance, reliability, and scalability.

Oracle Database is composed of the following elements:

• The Oracle software that you install on your host computer

• The database, which is a collection of physical files on one or more disks

  The database contains user data, metadata, and control structures. Metadata, or data about the data, is the collection of information about a disk that permits Oracle software to manage user data. An example of metadata is the data dictionary. Control structures (such as the control file and redo log) ensure the integrity, availability, and recoverability of user data.

• The Oracle instance, which is composed of the following:

  • The background processes, which are the operating system processes or threads that perform the work of accessing, storing, monitoring, and recovering user data, metadata, and control files associated with the database

  • The shared memory areas used by the background processes

• Server processes that perform work on behalf of connected users and applications, and the memory and temporary storage used by these processes

  Server processes parse and execute SQL statements, and retrieve and return results to the user or application.

• Oracle Net, which is a software layer that enables client applications and Oracle Database to communicate over a network, and the Oracle Net listener, which is a process that listens for connection requests from the network.

  Server processes parse and execute SQL statements, and retrieve and return results to the user or application.

  Common Oracle DBA Tasks

  As an Oracle DBA, you can expect to be involved in the following tasks:

  • Installing Oracle software

  • Creating Oracle databases

  • Performing upgrades of the database and software to new release levels

  • Starting up and shutting down the database

  • Managing the storage structures of the database

  • Managing users and security

  • Managing database objects, such as tables, indexes, and views

  • Backing up the database and performing recovery operations when necessary

  • Monitoring the state of the database and taking preventive or corrective action as required

  • Monitoring and tuning database performance

  • Diagnosing and reporting critical errors to Oracle Support Services

  In a small to medium-sized database environment, you might be the sole person performing these tasks. In large, enterprise environments, the job is often divided among several DBAs, each of whom has a specialty, such as database security or database tuning.