Question

1. Name and define the three capabilities used to describe distributed technology and databases.
2. What is the difference between replication and propagation?
3. What issues and constructs can cause data integrity problems after a LOAD?

Answer 1

Q1

Distributed Technology

1. System of components connected to each other without centralized control.
2. They are highly efficient and scalable.
3. Availability is High and less tolerant to failures.
4. Types:
   1. RPC (Remote procedure Calls):
   2. RMI (Remote Method Invocation):
   3. DCOM (Distributed Component Object Model)
   4. CORBA (Common Language Request Broker Architecture)

Distributed Database

1. Distributed databases are spread over multiple sites and not limited to a system
2. This is required when database need to be shared and accessed globally
3. The sites are loosely coupled and shares no physical components
4. Types of distributed database:
   1. Homogeneous Database: Identical storage by different sites.Easy to manage
   2. Heterogeneous Database: Different schema are used by different sites.Translations are required to communicate

Q2

Replication: It is a process of maintaining and copying the database objects around different database systems.Changes made are tracked and recorded before being pushed to other site.Using replication , it allows user to transact and query from different site if one site is not available.

Propagation: After the data is being replicated , it has to be updated among various replicas, this process is called propagation.Types

• Push bases propagation: pushes updates to other replica
• Pull based propagation: request other data to send a new replcia

Q3.

• Calculation of data or enforce constraints are being relied upon by database and application
• Unique constraint is not being confirmed by the data which was loaded