29-06-2012, 01:58 PM
Fundamentals of Relational Database Design andDatabase Planning
Fundamentals of Relational Database.ppt (Size: 188 KB / Downloads: 129)
DefinitionsWhat is a database?
A database is the implementation of freeware or commercial software that provides a means to organize and retrieve data. The database is the set of physical files in which all the objects and database metadata are stored. These files can usually be seen at the operating system level. This talk will focus on the organize aspect of data storage and retrieval.
Commercial vendors include MicroSoft and Oracle.
Freeware products include mysql and postgres.
For this discussion, all points/issues apply to both commercial and freeware products.
DefinitionsInstance
A database instance, or an ‘instance’ is made up of the background processes needed by the database software.
These processes usually include a process monitor, session monitor, lock monitor, etc. They will vary from database vendor to database vendor.
DefinitionsWhat is a schema?
A SCHEMA IS NOT A DATABASE, AND A DATABASE IS NOT A SCHEMA.
A database instance controls 0 or more databases.
A database contains 0 or more database application schemas.
A database application schema is the set of database objects that apply to a specific application. These objects are relational in nature, and are related to each other, within a database to serve a specific functionality. For example payroll, purchasing, calibration, trigger, etc. A database application schema not a database. Usually several schemas coexist in a database.
A database application is the code base to manipulate and retrieve the data stored in the database application schema.
Selecting a DBMSHow do I Choose?
Which database product is appropriate for my application? You must make a requirements assessment.
Does you database need 24x7 availability?
Is your database mission critical, and no data loss can be tolerated?
Is your database large? (backup recovery methods)
What data types do I need? (binary, large objects?)
Do I need replication? What level of replication is required? Read only? Read/Write? Read/Write is very expensive, so can I justify it?