OODBMS, MDDBMS

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OODBMS, MDDBMS

• Two emerging (emerged?) database technologies,
  and how they 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 star schema,
  but this breaks the object across multiple
  tables, and can introduce artificial keys
• Complex queries are difficult or sometimes
  impossible to write because SQL breaks the
  relational model
• Traditionally, could not represent files such as
  pictures, audio and video natively (only BLOB)

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OODBMS A Solution?

• Started in the 1980s
• Integrates database capabilities with OO
  programming language capabilities
• Makes database objects appear as programming
  language objects in an existing language (such as
  JAVA, C or Smalltalk)
• Relational Model is no longer valid objects are
  related through inheritance and polymorphism
• More of a persistent programming language than a
  DBMS

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Why Object Oriented?
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Benefits of OODBMS

• Explicit relationships improve the data access
  performance (especially as the database and
  complexity of the relationships grow) when
  compared to value based relationships.
• Supports a large number of different types of
  data, relationships, and objects with complex
  behavior
• A good fit for Knowledge Management problems,
  which are inherently complex
• Found application in telecommunications, high
  energy physics and subsets of financial services

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The drawbacks

• No clear standard
• (ODMG did come up with one, but it was not
  accepted by the major OODBMS vendors)
• Lack of interoperability with traditional RDBMS
  tools (such as OLAP, backup and recovery,
  reporting, etc)
• Seen by some as a lost opportunity to
  revolutionize software and database development
• Today, there are more products that perform
  object-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 the information we
  need in a complex query

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MDDBMS

• Multidimensional data model emerged over 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 with
  numerical measures, or as dimensions that
  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 price and amount
  purchased are numerical measures
• The type of product I bought, when I bought it,
  and where I bought it are all dimensions.

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MDDBMS cont

• Takes data from many sources, such as RDBMS,
  Legacy System, etc
• Data is physically stored on disk in a data
  structure that is highly optimized for
  multidimensional processing and fast retrieval
• Storage is between 2 and 10 times more efficient
  over RDBMS due to better indexing, compression
  and representation of sparse data

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MDDBMS (M)OLAP?

• Similar, but not the same
• MDDBMS is a database, and evolves with time as
  new data trickles in
• OLAP is a snapshot
• Both provide a multidimensional view of the data
• MOLAP tends to generate faster queries and uses
  less space than ROLAP or HOLAP

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Benefits

• Queries are simply a request to see pre-existing
  data organized in a specific fashion.
• Already highly organized, so the requested data
  is removed and reorganized
• Stores information in the same way that it is
  viewed (less data management, and maintenance)

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The drawbacks

• Not the best solution for every problem
• Works only on information with interrelations
• Database explosion with large amounts of sparse
  data (calculating all relationships can increase
  the database size dramatically).

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Summary

• OODBMS has little to do with KM (in fact, 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 Data Objects
  (JDO) http//java.sun.com/products/jdo/
• The OLAP Report http//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/h
  tManifesto/Manifesto.html

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Any

• Questions, comments, queries, concerns (or
  quotes)?