4f- Distributed Databases Security

Interception of Data
1. X- Fragmented and centralised databases have higher risk of interception as a lot more data is moving between sites
  1. Need high quality encryption.
2. O- Replicate databases only need to send small part of the database to be updated. It is more difficult to intercept the entire database
Physical Access to Data
1. X- Any place where data is stored need a full security system
  1. X- Costs increased for partitioned (fragmented) and replicated databases
2. O- In centralised databases only the central location needs high security as local sites do not store valuable information
Data Consistency and Integrity
1. Centralised
  1. O- All data is stored and updated in one place
  2. O- Only data changes at local sites is updating indexes with is straight-forward.
2. Vertically Fragmented
  1. O- Each non-key field is stored and updated in one place
  2. X- Need to make sure changes in primary key field are done at all sites
3. Horizontally Fragmented
  1. O- Each record is stored and updated in one place
  2. X- Need to make sure change in primary key does match an existing primary key.
4. Replicated Databases
  1. Changes made to the data are sent to each database rather than the new data it's self.
    1. E.g. is £450 is updated to £350inone location, -£100 is sent out to all databases for that cell.
  2. X- If Distributed Database Management System (DDMS) is not set up properly certain updates to data will be lost.
5. Data must be accurate and up-to-date. storing data at different locations may lead to problems with this as data changed at one site must also be changed in all the others.

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4f- Distributed Databases Security

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	Created by Gladys Mba over 7 years ago