Distributed Database Management Systems

Distributed Database Management System (DDBMS)
Governs storage and processing of logically related data over interconnected computer systems
Centralized Database Management System
Required that corporate data be stored in a single central site
Distributed Processing
Database’s logical processing is shared among two or more physically independent sites via network
Distributed Database
Stores logically related database over two or more physically independent sites via computer network
Database Fragments
Database composed of many parts in distributed database system
Transaction Processor (TP)(TM)(AP)
Software component of a system that requests
Data processor (DP)(DM)
Software component on a system that stores and retrieves data from its location
Single-Site Processing, Single-Site Data (SPSD)
Processing is done on a single host computer and data stored on host computer’s local disk
Mutliple-Site Processing, Single-Site Data (MPSD)
Multiple processes run on different computers sharing a single data repository
Mutliple-Site Processing, Multiple-Site Data (MPMD)
Fully distributed database management system
Integrate multiple instances of same DBMS over a network
Integrate different types of DBMSs
Fully Heterogeneous
Support different DBMSs, each supporting different data model
Distribution Transparency
Allows management of physically dispersed database as if centralized
Transaction Transparency
Ensures database transactions will maintain distributed database’s integrity and consistency
Two-Phase Commit Protocol (2PC)
Guarantees if a portion of a transaction operation cannot be committed, all changes made at the other sites will be undone
Performance Transparency
Allows a DDBMS to perform as if it were a centralized database
Failure Transparency
Ensures system will operate in case of a network failure
Network Latency
Delay imposed by the amount of time required for a data packet to make a round trip
Network Partitioning
Delay imposed when nodes become suddenly unavailable due to a network failure
Consistency, Availability, Partition Tolerance