6. Types of distributed database (3)

3. Partitioned + index

A modification of the partitioned database is to include an index of all remote database records as well. As shown below

This still partitions the database to keep all records as local as possible, but each store has an index pointing to records in all other databases. A central database keeps the indexes updated on a nightly batch run.

Advantage

• Still high performance as most queries and updates remain local
• Can efficiently access remote records by using the index rather than a network query to a central database

Disadvantage

• The system must now keep all indexes up to date
• More complicated