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Oracle DBA FAQ

A Oracle database administrator (DBA) directs or performs all activities related to maintaining a successful database environment. Responsibilities include designing, implementing, and maintaining the database system; establishing policies and procedures pertaining to the management, security, maintenance, and use of the database management system; and training employees in database management and use. A Oracle DBA is expected to stay abreast of emerging technologies and new design approaches. Typically, a Oracle DBA has either a degree in Computer Science and some on-the-job training with a particular database product or more extensive experience with a range of database products. A DBA is usually expected to have experience with one or more of the major database management products, such as Structured Query Language, SAP, and Oracle-based database management software.

What is Oracle Database Administrator?
A person responsible for the design and management of one or more databases and for the evaluation, selection and implementation of database management systems. In smaller organisations, the data administrator and database administrator are often one in the same; however, when they are different, the database administrator's function is more technical. The database administrator would implement the database software that meets the requirements outlined by the organisation's data administrator and systems analysts. Tasks might include controling an organisation's data resources, using data dictionary software to ensure data integrity and security, recovering corrupted data and eliminating data redundancy and uses tuning tools to improve database performance.

Why Learn Oracle Database Administration?
Data is at the center of today's applications; today's organizations simply cannot operate without data. In many ways, business today is data. Without data, businesses would not have the ability to manage finances, conduct transactions, or contact their customers. Databases are created to store and organize this data. The better the design and utility of the database, the better the organization will be positioned to compete for business.

Indeed, one of the largest problems faced by IT organizations is ensuring quality database administration. A survey of IT managers conducted by Information Week in December 2000 showed that the top two database management execution issues faced by companies are ease of administration and availability of qualified administrators.

Both of these issues were cited by 58% of survey respondents. Additionally, the 1999 Market Compensation Survey conducted by people3, a Gartner Company, shows that DBA positions take longer to fill than any other position. Clearly, there is no lack of demand for DBA skills in today's job market.

What are the personality traits of a Oracle DBA?
PERSONALITY TRAITS OF A DBA Many times managers concentrate on technical qualities and overlook personality. Virtually every category shown above means a DBA will have to interface with other personnel, be they vendors, users, developers or managers. This indicates the a DBA should exhibit the following traits:

* Self Confidence
* Curiosity
* Tenacity
* Tactful
* Self starter
* Detail oriented

Why are these traits important?
As a beginning DBA under a full-charge DBA this may be all right but if the person is the full--charge DBA then who are they going to depend on for their decisions if they have no self confidence? Interview questions should include ones on problems and how they were solved. The answers should demonstrate self confidence. One thing to remember is that it is not bad to not know an answer, but to not know where to find an answer is bad.

The Oracle database system is constantly changing. Not all of these changes are documented. Curiosity is a requirement to be a good DBA. If a DBA isn't curious they are passive and wait for things to be told them. A curious DBA will install the latest version and immediately begin searching out the differences and improvements and how they can be applied to make his or her job better (read easier). A curious DBA will have multiple references they purchased with their own money and will have read them. Curiosity will also drive them to understand the Oracle data dictionary and any utilities or packages provided by Oracle. Lack of knowledge about the data dictionary tables and views and the Oracle provided utilities and packages is unforgivable in a full--charge DBA.

Trouble shooting requires a bulldog like tenacity, getting a hold and not letting go until the problem is solved. Many times a DBA will give up on a problem that would have been solved with the next solution they tried.

A self-starting employee is important for any position. Doubly so for a DBA. A DBA must be able to wade in and make things happen, not just wait for things to happen. A self-starting DBA obtains or develops their own scripts to monitor such items as table sizes, tablespace usage, SGA usage in short, all of the items that can get them in trouble if ignored. Questions dealing with level of experience in PL/SQL, SQL and SQL*Plus will show how many scripts the DBA candidate has developed. Some operations in PL/SQL and SQL*Plus are generally only used by DBAs so questions concerning specific techniques will expose those who have written their own scripts and those who haven't.

Dealing with developers and managers, not to mention users, requires tact. A tactless DBA will make nothing but enemies for your department. Tact has been called the ability to tell someone to go to Hades and have them anxious for the trip. Many times developers, managers and users will make unreasonable requests, the DBA must have tact to field and deflect these requests without burning bridges. How a person acts during the interview process will show their level of tact.

The final trait, being detail--oriented, is very important. Being detail--oriented means that they don't have to be told to cross check details. It also means they actively document quirks in the installation "Just in case". The indications of a detail--oriented person are such things as bringing a daytimer or scheduler to the interview, showing up ahead of time, and asking questions that indicate they have researched the company they are interviewing with. This detail-orientation will show up in them knowing the Oracle internals and understanding the relationships between the views, tables and dynamic performance tables. Usually a detail--oriented person will take the time to research the database on their own.

What is a Database Architect?
Some organizations create a separate position, database architect, for design and implementation of new databases. The database architect is involved in new design and development work only; he is not involved in maintenance, administration, or tuning of established databases and applications. The database architect designs new databases for new or existing applications.

The rationale for creating a separate position is that the skills required for designing new databases are different from the skills required to keep an existing database implementation up and running. A database architect is more likely than a general-purpose DBA to have data administration and modeling expertise.

What is a Database Analyst?
Another common staff position is the database analyst. There is really no set definition for this position. Sometimes junior DBAs are referred to as database analysts. Sometimes a database analyst performs a role similar to that of the database architect. Sometimes the data administrator is referred to as the database analyst or perhaps as the data analyst. And sometimes a database analyst is just another term used by some companies instead of database administrator

What is a Data Modeler?
Data Modeler A data modeler is usually responsible for a subset of the DA's responsibilities. Data modeling tasks include the following:

* Collecting data requirements for development projects
* Analyzing the data requirements
* Designing project-based conceptual and logical data models
* Creating and updating a corporate data model
* Ensuring that the DBAs have a sound understanding of the data models

What is a Application DBA?
direct contrast to the system DBA is the application DBA. The application DBA focuses on database design and the ongoing support and administration of databases for a specific application or applications. The application DBA is likely to be an expert at writing and debugging complex SQL and understands the best ways to incorporate database requests into application programs. The application DBA must also be capable of performing database change management, performance tuning, and most of the other roles of the DBA. The difference is the focus of the application DBA—it is on a specific subset of applications rather than the overall DBMS implementation and database environment.

What is a Task-Oriented DBA?
Larger organizations sometimes create very specialized DBAs that focus on a specific DBA task. However, task-oriented DBAs are quite rare outside of very large IT shops. One example of a task-oriented DBA is a backup-and-recovery DBA who devotes his entire day to ensuring the recoverability of the organization's databases.

Most organizations cannot afford this level of specialization, but when possible, task-oriented DBAs can ensure that very knowledgeable specialists tackle very important DBA tasks.

Performance Analyst
Performance analysts are a specific type of task-oriented DBA. The performance analyst, more common than other task-oriented DBAs, focuses solely on the performance of database applications.

A performance analyst must understand the details and nuances of SQL coding for performance and be able to design databases for performance. A performance analyst will have very detailed technical knowledge of the DBMS so that he can make appropriate changes to DBMS and system parameters when required.

However, the performance analyst should not be a system DBA. The performance analyst must be able to speak to application developers in their language in order to help them facilitate appropriate program changes for performance.

The performance analyst is usually the most skilled, senior member of the DBA staff, a role that he has grown into due to his experience and the respect he has gained in past tuning endeavors.

What is a Data Warehouse Administrator?
Organizations that implement data warehouses for performing in-depth data analysis often staff DBAs specifically to monitor and support the data warehouse environment. Data warehouse administrators must be capable DBAs, but with a thorough understanding of the differences between a database that supports OLTP and a data warehouse. Data warehouse administration requires experience with the following:

* Business intelligence, query, and reporting tools
* Database design for read-only access
* Data warehousing design issues such as star schema
* Data warehousing technologies such as OLAP (including ROLAP, MOLAP, and HOLAP)
* Data transformation and conversion
* Data quality issues
* Data formats for loading and unloading of data
* Middleware

DBA role in Test and Production
At least two separate environments must be created and supported for a quality database implementation: test and production. Completely separating the test and production environments ensures the integrity and performance of operational work. New development and maintenance work can be performed in the test environment while operational applications are run in the production environment. Failure to separate test and production will cause development activities to impair the day-to-day business of your organization. Errant program code in the early stages of development could access or modify production data and cause production performance problems or invalid data.

The test and production environments need not be identical. While the production environment contains all of the data required to support the operational applications, the test environment needs only a subset of data required for acceptable application testing. Furthermore, the test DBMS implementation will usually not command the same amount of resources as the production environment. For example, less memory will be allocated to buffering and caches, data set allocations will be smaller and on fewer devices, and the DBMS software may be a more recent version in test than in production (to shake out any bugs in the DBMS code itself before it is trusted to run in production).

The test and production environments should be structured similarly though. Both environments should have access to the same system software because the programming staff needs to create applications in the same type of environment in which they will eventually run.

DBA role in Database Security and Authorization
Once the database is designed and implemented, programmers and users will need to access and modify the data. However, to prevent security breaches and improper data modification, only authorized programmers and users should have access. It is the responsibility of the DBA to ensure that data is available only to authorized users.

Typically, the DBA works with the internal security features of the DBMS in the form of SQL GRANT and REVOKE statements, as well as with any group-authorization features of the DBMS. Security must be administered for many actions required by the database environment:

* Creating database objects, including databases, tables, views, and program structures
* Altering the structure of database objects
* Accessing the system catalog
* Reading and modifying data in tables
* Creating and accessing user-defined functions and data types
* Running stored procedures
* Starting and stopping databases and associated database objects
* Setting and modifying DBMS parameters and specifications
* Running database utilities such as LOAD, RECOVER, and REORG

DBA role in Backup and Recovery
The DBA must be prepared to recover data in the event of a problem. "Problem" can mean anything from a system glitch or program error to a natural disaster that shuts down an organization. The majority of recoveries today occur as a result of application software error and human error. Hardware failures are not as prevalent as they used to be. In fact, analyst estimates indicate that 80% of application errors are due to software failures and human error. The DBA must be prepared to recover data to a usable point, no matter what the cause, and to do so as quickly as possible

DBA role in Data Integrity
A database must be designed to store the correct data in the correct way without that data becoming damaged or corrupted. To ensure this process, the DBA implements integrity rules using features of the DBMS. Three aspects of integrity are relevant to our discussion of databases: physical, semantic, and internal.

Physical issues can be handled using DBMS features such as domains and data types. The DBA chooses the appropriate data type for each column of each table. This action ensures that only data of that type is stored in the database. That is, the DBMS enforces the integrity of the data with respect to its type. A column defined as "integer" can only contain integers. Attempts to store non-numeric or non-integer values in a column defined as integer will fail. DBAs can also utilize constraints to further delineate the type of data that can be stored in database columns

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Source : http://tutorial.fyicenter.com/out.php?ID=192 | Oracle DBA

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What is Database Administrator?

Why Learn Database Administration?

What are the personality traits of a DBA?

Why are these traits important?

What is a Database Architect?

What is a Database Analyst?

What is a Data Modeler?

What is a Application DBA?

What is a Task-Oriented DBA?

What is a Data Warehouse Administrator?

DBA role in Test and Production

DBA role in Database Security and Authorization

DBA role in Backup and Recovery

DBA role in Data Integrity