DATABASE ADMINISTRATION WHAT IS IT?

THE GIST Database administrators are responsible for creating and maintaining the databases that form the core of business operations. They need to make sure the design of the databases is functional and appropriate, that the data in the databases is as accurate as possible, that the data is secure, that the data is accessible by those who need it when it is needed.

DUTY AREAS FOR A DATABASE ADMINISTRATOR Installing and upgrading database servers Designing, testing and maintaining databases Setting Database policies and Security Interacting with application developers Maintenance and Tuning Maintaining Availability Integrating data and data Analysis

INSTALLING AND/OR UPGRADING DATABASES An administrator often has to install new database servers or upgrade existing ones to a newer version. Both usually involve testing the environment first, but it is especially important with upgrades to make sure that the newer version does not disrupt existing data or conflict with existing applications.

DESIGNING TESTING AND MAINTAINING DATABASES The database administrator is usually involved with the design of any new databases. He or she may actually do the design, or they may simply review it. It is up to the administrator to set the policies for new databases, such as naming conventions, security conditions, degrees of normalization. Any database should be tested thoroughly before being brought on-line. The testing should ensure that the database meets all the business requirements that it was designed to meet, and that it conforms with all the policies. Once deployed the administrator sets policies for when and how often the database should be backed up, log shipping, failover clustering, etc.

SETTING DATABASE POLICIES AND SECURITY The database administrator set database policies for things like Naming conventions Back up policies Logins and security Maintenance policies Tuning and monitoring polices

INTERACTING WITH APPLICATION DEVELOPERS The database administrator will interact with application developers and set the terms for their accessing the databases It may be that they can only access databases through stored procedures and views or they may have to use pre defined services. Generally, applications will be tested for security and functionality before being deployed

MAINTENANCE AND TUNING Maintenance involves backing up and restoring database. It can also involve file maintenance. Controlling the growth of files. (Expanding or shrinking). Failover patterns, log shipping and server clusters may also need to be maintained. Tuning involves making sure that data can be accessed and utilized as quickly as possible. This can involve creating indexes on fields often used as search criteria. It can also involve “denormalization,” restructuring tables to speed up searches. It also means managing concurrency and load. Monitoring the database enables the database administrator to analyze where changes need to be made to increase performance

MAINTAINING AVAILABILITY Availability is the term that refers to keeping databases up and running for as long as they are needed. Almost universally this now means 24 hours a day, 7 days a week. Machines and databases need maintenance, so the only way to do this effectively is to have multiple machines running multiple copies of a database, so that when one is taken off line another can take over its load. Clustering, log shipping, mirroring are tools for helping to maintain availability. Clusters of servers with the same databases are kept in sync by log shipping— copying the log file of a server to another server so it has a transcript of all the database transactions. When one server fails another steps into its place. This is called failover. Mirroring is a especially safe but expensive means of ensuring failover. It requires 3 servers: one is the active server, one is the copy of the active server and the third is a monitor that checks the health of the active server and should something happen switches to the copy.

INTEGRATING DATA AND DATA ANALYSIS Another big task for Database Administrators can be to get data, which may come from many disparate sources, both structured and unstructured, into the databases. The data often has to be cleaned, rearranged and converted before it can be loaded into the database tables. Exporting the data can be complex also, though usually less challenging. Having data in a database is fine, but it is not particularly useful until it is analyzed. It may fall to the database administrator to analyze the data for business trends or just to create the data warehouses for others to do the analysis.