Advanced Topics

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Chapter 9

• Advanced Topics

Database Management
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Objectives

• Describe distributed database management systems.
• Discuss client/server systems.
• Define data warehouses and explain their uses.
• Discuss the general concepts of object-oriented
  database management systems.
• Summarize the impact of the Internet and
  intranets on database management systems.

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Distributed Databases

• Computers installed at various sites must be
  connected in some kind of communications network.
• A distributed database is a single logical
  database that is physically distributed to
  computers on a network.
• DDBMS is capable of supporting and manipulating
  distributed databases.

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Figure 9.1 Communications Network
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Characteristics ofDistributed DBMSs

• Homogeneous DDBMS has the same local DBMS at each
  site.
• Heterogeneous DDBMS has at least two sites where
  the local DBMSs are different.

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Characteristics ofDistributed DBMSs

• Location transparency feels to a user as though
  the entire database is at their location.
• Replication transparency is where the user is
  unaware of the behind the scenes replication of
  the data.
• Fragmentation transparency is where a local
  object can be divided among the various locations
  on the network.

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Figure 9.2 Premiere Products Customer Data,
Including Site Number
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Figure 9.3 Fragmentation of Customer Data by Site
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Figure 9.4Advantages of Distributed Databases
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Figure 9.5Disadvantages of Distributed Databases
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Rules for Distributed Systems

• Sites should be autonomous.
• No master site.
• No need for planned shutdowns.
• Location transparency.
• Replication transparency.
• Query processing

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Rules for Distributed Systems

• Update management.
• Not dependent on a specific hardware.
• Not dependent on a specific operating system.
• Not dependent on a specific network.
• Not dependent on a specific DBMS.

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Figure 9.6Client/Server Systems

• File server contained files required by the
  individual workstations on the network.

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Figure 9.7Client/Server Systems

• Client/Sever has the DBMS run on the file server,
  but the user sends requests for specific data,
  not files.

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Advantages ofClient/Server Systems

• More efficient than file server systems.
• Possibility of distributing work among several
  processors.
• Workstations need not be as powerful.
• The user doesnt need to learn any special
  commands or techniques.

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Advantages ofClient/Server Systems

• Easier for users to access data from a variety of
  sources.
• Provides greater level of security than file
  server systems.
• Powerful enough to replace expensive mainframe
  applications.

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Data Warehouses

• A subject-oriented, integrated, time- variant,
  nonvolatile collection of data in support of
  managements decision-making process.

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Figure 9.8 Data Warehouse Architecture
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Figure 9.9 Data Warehouse Structure
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On-Line Analytical Processing(OLAP) Rules

• Multidimensional conceptual view.
• Transparency.
• Accessibility.
• Consistent reporting performance.
• Client/server architecture.
• Generic dimensionality

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On-Line Analytical Processing(OLAP) Rules

• Dynamic sparse matrix handling.
• Multiuser support.
• Unrestricted, cross-dimensional operations.
• Intuitive data manipulation.
• Flexible reporting.
• Unlimited dimensions and aggregation levels

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Object-Oriented Database Management Systems

• OODBMS is a system in which data and the methods
  that operate on data are encapsulated into
  objects.

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Figure 9.10 Premiere Products Sample Data
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Figure 9.11 An Object-Oriented Representation
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Figure 9.12 Underlying Relations for the Premiere
Products Database
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Figure 9.13 Two Methods for the Premiere
Products Object-Oriented Database
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Rules for Object-Oriented Systems

• Complex objects.
• Object identity.
• Encapsulation.
• Types or classes.
• Inheritance.
• Late binding.
• Computational completeness.

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Rules for Object-Oriented Systems

• Extensibility.
• Persistence.
• Performance.
• Shared update support.
• Recovery support.
• Query facility.

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Figure 9.14The Internet and Intranets