Unit 4.5 - Databases and Distributed Systems

• Database


  A collection of related data or information stored in a logical and structured way
• Distributed Systems


  Services are separated across many servers or computers, databases are often from the main application
• Distributed systems operate by the application server communicating with the database when processing data
• Advantages of Distributed Systems

  • Separate custom servers can be created to closely meet the requirements for the application and the database
  • If the database server fails, the application can continue to run
  • Improved security due to more protection limits
  • Backups have less impact on end users
• Distributed Databases


  The splitting of a database across multiple servers
• Transactions in a distributed database are more complex. They use an all or nothing approach so if one database is unable to update, no changes are made
• Advantages of Distributed Database

  • Resilience: if a database fails, other areas of the database are unaffected
  • Security: access to the entire system is limited
  • Scaling: new servers and databases can easily be added
  • Performance: the load on a single database is spread across many servers