Understanding Database Schemas and Dimensions
This chapter covers portions of Objective 1.1 (Identify basic concepts of data schemas and dimensions) of the CompTIA Data+ exam and includes the following topics:
Snowflake and star schemas
Slowly changing dimensions
Keeping current information
Keeping historical information
For more information on the official CompTIA Data+ exam topics, see the Introduction.
This chapter covers topics related to database schemas, particularly snowflake and star schemas. In addition, it explores the importance of keeping database information in current and historical formats.
We have already established the fact that data is a key component for business growth and to accelerate the presence in today’s competitive market. Due to the increasing focus on the value of data, organizations are collecting massive volumes of data—running into petabytes—across data warehouses and data lakes.
Data is most useful if it is stored in a structure that is easy to understand and gives logical descriptions of and shows relationships between data objects. A schema represents the structure of the database. It shows how the data is arranged and the relationships among the data objects, such as tables, fields, packages, views, relationships, primary keys, and foreign keys. A schema is not data; rather, it provides information about the structure of data and relationships among tables or models. A database schema specifies which tables or relationships form a database and the fields included in each table.