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OODBMS, MDDBMS
Two emerging (emerged?)database technologies, and howthey relate to Knowledge
Management
Sean Sullivan
100046263
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Outline
Issues with RDBMS
OODBMS
Benefits, drawbacks
MDDBMS
Benefits, drawbacks
OLAP, MOLAP
Summary
Questions
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Relational Databases
Have problems with redundancy
Could normalize the data to create a starschema, but this breaks the objectacross multiple tables, and can introduceartificial keys
Complex queries are difficult or
sometimes impossible to write becauseSQL breaks the relational model
Traditionally, could not represent filessuch as pictures, audio and video
natively (only BLOB)
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OODBMS: A Solution?
Started in the 1980s
Integrates database capabilities with OOprogramming language capabilities
Makes database objects appear asprogramming language objects in an existinglanguage (such as JAVA, C++ or Smalltalk)
Relational Model is no longer valid: objects arerelated through inheritance and polymorphism
More of a persistent programming languagethan a DBMS
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Why Object Oriented?
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Benefits of OODBMS
Explicit relationships improve the data accessperformance (especially as the database andcomplexity of the relationships grow) when
compared to value based relationships. Supports a large number of different types of
data, relationships, and objects with complexbehavior
A good fit for Knowledge Managementproblems, which are inherently complex
Found application in telecommunications, highenergy physics and subsets of financial services
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The drawbacks
No clear standard
(ODMG didcome up with one, but it was not acceptedby the major OODBMS vendors)
Lack of interoperability with traditional RDBMStools (such as OLAP, backup and recovery,reporting, etc)
Seen by some as a lost opportunity to
revolutionize software and databasedevelopment
Today, there are more products that performobject-sql maping than there are pure OODBMS
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Relational Database (revisited)
Represents data in a table
Think of displaying this information
in a spreadsheet Requires indexing and sorting which
takes time
SQL may not be able to get theinformation we need in a complexquery
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MDDBMS
Multidimensional data model emergedover the past 10-15 years
MDDBMS is the Rubik's Cube of
database management systems Focuses on analyzing the data, not
recording transactions
Data is categorized as either facts withnumerical measures, or as dimensionsthat characterize the fact
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Example
I decide to buy an AMD 64 3500+processor from http://tigerdirect.ca
The purchase is a fact; the priceand amount purchased arenumerical measures
The type of product I bought, whenI bought it, and where I bought itare all dimensions.
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MDDBMS cont
Takes data from many sources, such asRDBMS, Legacy System, etc
Data is physically stored on disk in adata structure that is highly optimizedfor multidimensional processing and fastretrieval
Storage is between 2 and 10 times moreefficient over RDBMS due to betterindexing, compression andrepresentation of sparse data
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MDDBMS = (M)OLAP?
Similar, but not the same
MDDBMS is a database, and evolveswith time as new data trickles in
OLAP is a snapshot
Both provide a multidimensional view ofthe data
MOLAP tends to generate faster queriesand uses less space than ROLAP orHOLAP
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Benefits
Queries are simply a request to seepre-existing data organized in aspecific fashion.
Already highly organized, so therequested data is removed andreorganized
Stores information in the same waythat it is viewed (less datamanagement, and maintenance)
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The drawbacks
Not the best solution for everyproblem
Works only on information withinterrelations
Database explosion with largeamounts of sparse data (calculating
all relationships can increase thedatabase size dramatically).
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Summary
OODBMS has little to do with KM (infact, there is just plan very little
work being done in this field). MDDBMS are an important tool in
KM, and, although are not perfect,will be around for a while
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Links of Interest
Object persistence in Java: Java DataObjects (JDO)
http://java.sun.com/products/jdo/
The OLAP Reporthttp://www.olapreport.com/
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References
Colliat, G. (1996). OLAP, relational,and multidimensional database
systems ACM Press, 25(3), 64-69. http://wikkipedia.org
http://olapreport.org
http://cs.cmu.edu/People/clamen/OODBMS/Manifesto/htManifesto/Manifesto.html
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Any
Questions, comments, queries,concerns (or quotes)?
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