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DISTRIBUTED PROCESSING
&
DISTRIBUTED DATABASES
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DISTRIBUTED DATABASES
When the computer system and the databases arefound at one location, they are called centralizeddatabases,
when they are scattered they are called distributeddatabase systems
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DISTRIBUTED PROCESSING
Distributed processing can be defined as a system inwhich both computer power and data occur at more
than one site, and application programs are run at
more than one site
Earlier distributed processing systems were
considered uneconomical because of the economies
of scale associated with large centralized computer
systems
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DISTRIBUTED DATABASES When processing is distributed, then data too needs
to be distributed and made available at the differentlocations.
There are two ways of doing this
Replicated databases
- provide duplicates of all data at all sites
Partitioned databases
- data may be divided into segments and madeavailable to diff locations. Partition could be alongfunctional lines, sales, finance etc or geographical lines
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ADVANTAGES & DISADVANTAGES
Distributed databases reduce costs of transferringdata to diff sites
Provide faster response time for filling forms etc.
However problems of control are compounded Problems of security are increased
Data redundancy occurs and consistency iscompromised
When managers download data from a centralizeddatabase to their own computers, it is no longercentralized
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REASONS FOR IMPLEMENTATION
Improved response time Reduced costs
Improved accuracy
Reduced mainframe costs Smoother growth
Increased reliability
Resource sharing
Increased user satisfaction
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CONCERNS FOR MANAGERS
Lack of professional MIS staff Standardization
Documentation
Data loss Security
Data consistency
System maintenance
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AN EFFECTIVE SYSTEM
Distributed processing systems have to be managedcarefully in order to be effective.
The systems should: Be easy to use.
Users should not have to know where the data is, or which
processors need to be used
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CLIENT / SERVER COMPUTING
This is most commonly used now a days. Theapplication processing is divided between a client
which is generally a PC and a server, which may be
a file server on a local area network or a
minicomputer or a mainframe.
The client processes run on the PC and make
requests of the server processes, which may run on
several platforms
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SQL SERVERS An SQL server is a software package that runs on a
dedicated networked computer The SQL server computer usually devotes all its energies to
managing the database software and does not handle othernetwork tasks
SQL server software performs database applications fasterand more reliably than typical LAN based databasemanagement software
A client workstation may ask SQL server software to send allrecords that match certain selection parameters. The SQL
server software will process the request at the server andsend only those records that fit the parameters
In client server computing, the back end processor providesaccess to the database and a variety of database servicessuch as remote connectivity and data security
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DOWNSIZING
Makes available the data in any of the organizationsdatabases to any one with a microcomputerworkstation
Because of their power and efficiency, client server
computing systems running on LANs have beenreplacing mainframe bases information systems inmost organizations
Most organizations are downsizing to LAN basedclient server computer systems from older legacysystems
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THANK YOU
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Practice Questions Q1. Explain the term distributed processing? How does distributed
processing differ from a distributed database.
Q2. Is it necessary for organization to implement distributed processing?Support your answer by Giving Reason
Q3. What are the two basic ways to distribute database? Explain how thismethod differs?
Q4. Why might an organization want to have a distributed database system?
Q5. What problem distributed database system might generate for anorganization?
Q6. Explain how client / server information systems can help managers
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