Database Administrator Roles and Responsibilities

A Database Admininstrator, Database Analyst or Database Developer is the person responsible for managing the information within an organization. As most companies continue to experience inevitable growth of their databases, these positions are probably the most solid within the IT industry. In most cases, it is not an area that is targeted for layoffs or downsizing. On the downside, however, most database departments are often understaffed, requiring adminstrators to perform a multitude of tasks.

Depending on the company and the department, this role can either be highly specialized or incredibly diverse. The primary role of the Database Administrator is to adminster, develop, maintain and implement the policies and procedures necessary to ensure the security and integrity of the corporate database. Sub roles within the Database Administrator classification may include security, architecture, warehousing and/or business analysis. Other primary roles will include:

• Implementation of data models
• Database design
• Database accessibility
• Performance issues
• Capacity issues
• Data replication
• Table Maintainence

Database Administrators are often on-call and required to work as needed. This position carries an enormous amount of responsibility.

UNDO SPACE ACQUISITION AND MANAGEMENT

When you open the database , the instance e attempts to acquire one or more tablespaces or roll back, segments you determine whether to operate in automatic undo management mode or manual undo management mode at instance start up using the UNDO_MANAGEMENT initialization parameter. The supported values are AUTO or MANUAL, if AUTO , then the instance is started in automatic undo management mode. The default value is MANUAL.


1) If you use the undo tablespace method, you are automatic, undo management mode,. This is recommended.

2)If you use the rollback segment method of managing undo sapce, then you are using manual undo management mode.

Instance Recovery

If the database was last closed abnormally(say Shutdown Abort) either because the database administrator terminated its instance of because of a power failure, then Oracle automatically performs recovery when the database is re opend.

DATABASE ADMINISTRATOR

is a person responsible for the design, implementation, maintenance and repair of an organization's data base are also known by the titles Database Coordinator or Database Programmer, and is closely related to the Database Analyst, Database Modeler, Programmer Analyst, and Systems Manager. The role includes the development and design of database strategies, monitoring and improving database performance and capacity, and planning for future expansion requirements. They may also plan, co-ordinate and implement security measures to safeguard the database.^[Employing organizations may require that a database administrator have a certification or degree for database systems (for example, the Microsoft Certified Database Administrator).

How a Database is Mounted

The instance mounts a database to associate the database with that instance. To mount the database the instance control files and opens them.Control files are specified are in the CONTROL_FILES initialization parameter in the parameter file used to start the instance.Oracle then reads the control files to get the names of the database's and redo log files. At this point, the database is still closed and is accessible only to the database administrator. The administrator can keep the database closed while completing specific maintenance operations. However the database is not yet available for normal operations.

How a Clone Database is Mounted.

A clone database is a specified copy of a database that can be used for tablespace point-in-time recovery. When you perform tablespace point-in-time recovery, you mount the clone database and recover the tablespaces to desired time, then export metadata from the clone to the primary database and copy the data files from the recovered tablespaces.

How Database Is Mounted

The Instance mounts a database to associate the database with that instance.To mount the database.the instance finds the database control files and opens them.Control files are specified in the CONTROL_FILES initialization parameter in the parameter file used to start the instance.Oracle then reads the control files to get the names of the database's data files and redo log files.At this point, the database is still closed and is accessible only to database administrator. The database administrator can keep the database closed while completing specific maintenance operations. However , the database is not yet available for normal operations.

How a Clone Database Is Mounted

A clone database is a specialized copy of a database that can be used for tablespace point-in-time recovery . When you perform tablespace point-in-time recovery. you mount the clone database and recover the tablespace to the desired time. then export meta data from the clone to the primary database and copy the data files from the recovered tablespaces.

Restricted Mode of Instaance Startup

You can start an instance in restricted mode(or later alter an existing instance to be in restrcted mode). This restricts connections to only those users who have been granted the RESTRICTES SESSION system privilege.

Forced Startup in Abnormal Situations

In unusual circumstances , a previous instance might not have been shut down cleanly. For example, one of the instance's processes might not have terminated properly . In such situations, the database can return an error during normal instance startup. To reslove this problem, You must terminate all remnant Oracle processes of the previous instance before starting the new instance.