4d - Distributed Databases

4d - Distributed Databases

1. Partitioned Databases

   • Horizontal Partitioning
     • Data is separated across sites based upon records
     • Each site can search for records stored at other sites using a global search
     • Often separated by location/region
   • Vertical Partitioning
     • Data is separated across sites based upon fields
     • Each site can search locally for its own data & can also perform global search to find data stored at other sites
     • Often separated by sector, e.g. finance
   • Different parts of data stored at different sites

2. Replicated Databases

   • This is the copy of the database with is stored at each site within the network
   • Each site can search for any records locally without performing a global search

3. Central Database with Remote Local Indexes

   • Database is only stored in one single location but has indexes at each site
   • The index is used to improve search time for data because each site can search for a record's location at its own site and then simply request that record from the location at the central database
   • The index will contain the key field that can be searched and the address of the record in the central database