Database Administrator (DBA)

 

A database administrator (DBA) is a person who is responsible for the environmental aspects of a database. In general, these include:

·Recoverability – Creating and testing Backups

·Integrity – Verifying or helping to verify data integrity

·Security – Defining and/or implementing access controls to the data

·Availability – Ensuring maximum uptime

·Performance – Ensuring maximum performance

·Development and testing support – Helping programmers and engineers to efficiently utilize the database.

 

The role of a database administrator has changed according to the technology of database management systems (DBMSs) as well as the needs of the owners of the databases.

For example, although logical and physical database designs are traditionally the duties of a database analyst or database designer, a DBA may be tasked to perform those duties.

 

Types of Database Administration

There are three types of DBAs:

1. Systems DBAs (sometimes also referred to as Physical DBAs, Operations DBAs or Production Support DBAs)

2. Development DBAs

3. Application DBAs

 

Depending on the DBA type, their functions usually vary. Below is a brief description of what different types of DBAs do:

 

Roles of DBA

Some of the roles of the DBA may include:

·Installation of new software — It is primarily the job of the DBA to install new versions of DBMS software, application software, and other software related to DBMS administration. It is important that the DBA or other IS staff members test this new software before it is moved into a production environment.

·Configuration of hardware and software with the system administrator — In many cases the system software can only be accessed by the system administrator. In this case, the DBA must work closely with the system administrator to perform software installations, and to configure hardware and software so that it functions optimally with the DBMS.

·Security administration — One of the main duties of the DBA is to monitor and administer DBMS security. This involves adding and removing users, administering quotas, auditing, and checking for security problems.

·Data analysis — The DBA will frequently be called on to analyze the data stored in the database and to make recommendations relating to performance and efficiency of that data storage. This might relate to the more effective use of indexes, enabling “Parallel Query” execution, or other DBMS specific features.

·Database design (preliminary) — The DBA is often involved at the preliminary database-design stages. Through the involvement of the DBA, many problems that might occur can be eliminated. The DBAknows the DBMS and system, can point out potential problems, and can help the development team with special performance considerations.

·Data modeling and optimization — by modeling the data, it is possible to optimize the system layout to take the most advantage of the I/O subsystem.

·Responsible for the administration of existing enterprise databases and the analysis, design, and creation of new databases.

 

 

- Data modeling, database optimization, understanding and implementation of schemas, and the ability to interpret and write complex SQL queries

- Proactively monitor systems for optimum performance and capacity constraints

- Establish standards and best practices for SQL

- Interact with and coach developers in SQL scripting

 

Functions

1. Selection of hardware and software

  • Keep up with current technological trends
  • Predict future changes
  • Emphasis on established off the shelf products

2. Managing data security and privacy

  • Protection of data against accidental or intentional loss, destruction, or misuse
  • Firewalls
  • Establishment of user privileges
  • Complicated by use of distributed systems such as internet access and client/ server technology.

 

 

Schema Definition
The Database Administrator creates the database schema by executing DDL statements.  Schema includes the logical structure of database table(Relation) like data types of attributes,length of attributes,integrity constraints etc.

Storage structure and access method definition 
Database tables or indexes are stored in the following ways: Flat files,Heaps,B+ Tree etc..

Schema and physical organization modification
The DBA carries out changes to the existing schema and physical organization.

Granting authorization for data access
The DBA provides different access rights to the users according to their level. Ordinary users might have highly restricted access to data, while you go up in the hierarchy to the administrator ,you will get more access rights.

Routine Maintenance
Some of the routine maintenance activities of a DBA is given below.

Taking backup of database periodically
Ensuring enough disk space is available all the time.
Monitoring jobs running on the database.
Ensure that performance is not degraded by some expensive task submitted by some users.
Performance Tuning

Responsibilities of DBA.

1)      Interaction with manager: the raw data is stored on the disk using file system which is unusually provided by a conventional operating system. The data base manager transaction the various DML statements into low level file system commands. The Database manager is responsibility for the actual storage retrieval and updating of data.

2)      Integrity enforcement: the data values stored in data base must satisfied certain types of consistency types of consistency constraints. All the validation and condition apply to database should be clearly defined.

3)      Security enforcement: each and every user of data base need not to have the access the entire database. It is to have the access the entire database it I the job of database manager to enforce security requirements.

4)      Backup and Recovery: a computer system like any other mechanical device is subject to failure there are verities of courses of such failure including disk crash. Power failure software errors. In each of these causes it is the responsibility of database manager to detect such failure and restored the database as before.

5)      Concurrency control: when several user update database concurrently. The consistency of data may no longer be preserved. It is necessary for the system to control interaction among the concurrent users are achieving such a control is one of the responsibility of data base manager.

6)      Query Processor: the data base user retrieve data by formulating a query in a data manipulating language provided by database. The query processor is used to interpretation online user query and converts it into an effective series of operation in base manager for execution. The query processes the structure of relevant portion of data base and uses this information in modifying a query and preparing an optimal path to access the database.

7)      Data base administrator: the person having total control over the system is called DBA.  The DBA has three level of data base and in consultation with the overall user community, sets up the definition of global view or conceptual view of data base it has following responsibility:-

  • Schema definition
  • Storage structure and access method definition
  • Schema and physical organization modification
  • Granting of authorization for data access.
  • Integrity constraint specification.

 

 

Types of DBA

  1. Administrative DBA – Work on maintaining the server and keeping it running. Concerned with installation, backups, security, patches, replication, OS configuration and tuning, storage management etc. Things that concern the actual server software.
  2. Development DBA - works on building queries, stored procedures, etc. that meet business needs. This is the equivalent of the programmer. You primarily write T-SQL or PL-SQL.
  3. Database Architect – Design schemas. Build tables, FKs, PKs, etc. Work to build a structure that meets the business needs in general. The design is then used by developers and development DBAs to implement the actual application.
  4. Data Warehouse DBA - responsible for merging data from multiple sources into a data warehouse. May have to design warehouse, but cleans, standardizes, and scrubs data before loading. In SQL Server, this DBA would use SSIS heavily.
  5. OLAP DBA – Builds multi-dimensional cubes for decision support or OLAP systems. The primary language in SQL Server is MDX, not SQL here
  6. Application DBA- Application DBAs straddle the fence between the DBMS and the application software and are responsible for ensuring that the application is fully optimized for the database and vice versa. They usually manage all the application components that interact with the database and carry out activities such as application installation and patching, application upgrades, database cloning, building and running data cleanup routines, data load process management, etc

 

 

 

 

 

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