centralised and distributed databases
DESCRIPTION
Centralised and distributed databasesTRANSCRIPT
Centralised Database
Centralised Database
A single central database accessed by multiple users
+ Easier to organise, edit, query and backup
- Can be slower because of high usage / load
Distributed Database
Distributed Database
Database split into multiple files
+ Data access and retrieval faster at nearest points
- Can be slower accessing non local data
- Need to be ensure data is consistent / synchronised
Distributed Database
Vertical Partitioning
Split the database to improve speed
• Group commonly queried fields together• Physically closer together therefore faster to retrieve
Distributed Database
Horizontal Partitioning
Split the database according to a specific criteria
• Tables have exactly the same structure• Organise database geographically / by region
Replication
All data copied to all locations in the organisation
Data is processed on local copies of the database
Any changes copied to central database when low usage (e.g. night)
Central Index
Database index is held centrally, which then links to actual data
+ Don’t store all the data in the main database so it is not frequently updated
- May be a delay in retrieving data from actual database
Data Warehouse / Data MiningInvestigate
What is meant by a data warehouse
What is meant by data mining
CreditsHigher Information Systems – Using Information – Centralised and Distributed Databases
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