CSE 4202: Database Systems Design & Information Management Systems 2 - Session 06

Flashcards covering the fundamentals of Distributed Database Management Systems (DDBMS), including components, transparency levels, distribution architectures, and design strategies.

Distributed Database Management System (DDBMS)

A system that governs the storage and processing of logically related data over interconnected computer systems in which both data and processing are distributed among several sites.

Centralized Database Management System

A structure from the 1970s that requires corporate data to be stored in a single central site, usually a mainframe computer.

Distributed Processing

A system where a database’s logical processing is shared among two or more physically independent sites connected through a network, even if it uses only a single-site database.

Database Fragments

Parts of a distributed database located at different sites that can be replicated among various sites and are managed by their local database process.

Transaction Processor (TP)

The software component in each computer or device that requests data; also known as the application processor (AP) or the transaction manager (TM).

Data Processor (DP)

The software component residing on each computer or device that stores and retrieves data located at the site; also known as the data manager (DM).

Single-Site Processing, Single-Site Data (SPSD)

A configuration where the functions of the TP and the DP are embedded within the DBMS located on a single computer.

Multiple-Site Processing, Single-Site Data (MPSD)

A configuration where multiple processes run on different computers sharing a single data repository, usually requiring a network file server.

Multiple-Site Processing, Multiple-Site Data (MPMD)

A fully distributed DBMS with support for multiple data processors and transaction processors at multiple sites.

Homogeneous DDBMS

A system that integrates only one type of centralized DBMS over a network.

Heterogeneous DDBMS

A system that integrates different types of centralized DBMSs over a network, potentially supporting different data models.

Distribution Transparency

A feature that allows a distributed database to be treated as a single logical database, hiding partitioning, replication, and data location from the user.

Transaction Transparency

A property that ensures transactions maintain integrity and consistency by completing only when all involved sites complete their part of the transaction.

Failure Transparency

A feature ensuring the system continues to operate in the event of a node failure, with lost functions picked up by another network node.

Performance Transparency

Allows a system to perform as if it were a centralized DBMS and ensures it finds the most cost-effective path to access remote data.

Heterogeneity Transparency

A feature that allows the integration of several different local DBMSs under a common, or global, schema.

Fragmentation Transparency

The highest level of transparency where neither fragment names nor fragment locations are specified prior to data access.

Location Transparency

A level of transparency where the user or programmer must specify database fragment names but does not need to specify their locations.

Local Mapping Transparency

The lowest level of distribution transparency where the user must specify both fragment names and their physical locations.

Distributed Data Dictionary (DDD)

Also known as a Distributed Data Catalog (DDC), it contains the description of the entire database as seen by the administrator, including the global schema.

Distributed Global Schema

The common database schema used by local TPs to translate user requests into subqueries (remote requests) for different DPs.

Two-Phase Commit Protocol

A transaction management protocol consisting of Phase 1 (Preparation) and Phase 2 (Final COMMIT), requiring DO-UNDO-REDO and write-ahead protocols.

Replica Transparency

The ability of a DDBMS to hide the existence of multiple copies of data from the user.

Mutual Consistency Rule

A rule in data replication requiring that all copies of data fragments across the network must be identical.

Data Fragmentation

A strategy to break a single object, like a table, into two or more segments, which can be horizontal, vertical, or mixed.

Data Allocation

The process of deciding where to locate data, categorized as centralized, partitioned, or replicated.

Local Site Independence

The principle from C.J. Date’s rules stating each local site can act as an independent, autonomous, centralized DBMS.