Download - Object Oriented Database Management System
OUTLINE
Types of database Object oriented database Objects Comparison of oodbs and rdbs Conclusion References
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DIFFERENCES
The first database systems (early ‘60s and before) used a hierarchical arrangement where, for example, parts were stored as sub-elements of the supplier that supplied them.
This approach had several disadvantages, including the introduction of an unnecessary degree of asymmetry.
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DIFFERENCES
To overcome the asymmetry problem, network databases (mid ‘60s) came into being.
These were mainly pointer-based structures. Querying and traversal was a low-level procedural affair.
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DIFFERENCES
Relational systems were born in 1969 and were soon recognised as a drastic simplification over the previous models.
Everyone agreed that relational was a good thing.
However it took a good decade before the commercial systems could catch up with the theory.
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DIFFERENCES
The late ‘80s saw the emergence of object oriented database systems as a response to the requirements of applications like CAD which dealt with many complex, nested objects.
The field is still evolving very rapidly and, although everyone agrees that some degree of objectness is useful, there is no unanimous consensus on what exactly an OODBMS should be.
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OBJECT ORIENTED DATABASE
Object-Oriented DBMS(OODBMS) are DBMS based on an ObjectOriented Data Model inspired by OO programming languages
OODBMS are capable of storing complex objects, I.e., objects that are composed of other objects, and/or multi-valued attributes
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OBJECT ORIENTED FEATURES
User-defined data types
Nested objects
Containers: sets, lists, bags...
Methods (precursor: stored procs)
Preserve strong typing across interface
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KEY BENEFITS OF ODBMS
Sharing in highly distributed environment Easier to share and distribute objects than tables
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KEY BENEFITS OF ODBMS
Better memory usage and less paging 1. Bringing only objects of interest Object-oriented
databases can reduce the need for paging b
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STRENGTHS
Rich type system
Better at modelling complex objects
Better performance on certain data structures
No impedance mismatch
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OBJECTS
Objects are used in object oriented languages such as C++, Java, and others.
Objects basically consist of the following:
Attributes - Attributes are data which defines the characteristics of an object. This data may be simple such as integers, strings, and real numbers or it may be a reference to a complex object.
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OBJECTS Methods - Methods define the behavior of an object and
are what was formally called procedures or functions.
Therefore objects contain both executable code and data.
There are other characteristics of objects such as whether methods or data can be accessed from outside the object.
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WHEN TO USE OBJECT DATABASES
Object databases should be used when there is complex data and/or complex data relationships.
This includes many to many object relationship.
Object databases should not be used when there would be few join tables and there are large volumes of simple transactional data.
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WHY OBJECT-ORIENTED DATABASES?
Because object-oriented databases are good at handling BLOBs, and the new world of information is all about BLOBs.
BLOB - Binary Large Object. Like:
• Images • Video • Audio • Animations• Mixed Media
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DIFFERENT FROM RDBS An OOD and its database management system (DBMS) is
aware of how to
Access or extract internal components of an object. For example, one or two frames of a video.
Execute operations or functions against objects without exporting them to the client.
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DIFFERENT FROM RDBS Extract enough about the object to develop an "intelligent"
search plan to optimize performance.
For example: The user wants multiple frames of a video, plus info on actors, royalties and rights.
The OODBMS gauges the speed of retrieval for each item and optimizes a retrieval plan using SERVER resources, freeing the client to continue work.
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HOW DATA IS STORED Two basic methods are used to store objects by different
database vendors
Each object has a unique ID and is defined as a subclass of a base class, using inheritance to determine attributes.
Virtual memory mapping is used for object storage and management.
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COMPARISON
Criteria RDBMS ODBMS
Support for object oriented
programming
Poor Direct and extensive
Simplicity of use Table structures easy to
understand
OK for programmers; some
SQL access for end users
Extensibility and content None users can write methods and
on any structure
Complex data relationships Difficult to model Can handle arbitrary
complexity
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ADVANTAGES OVER RDBMS
Reduced paging
Better concurrency control - A hierarchy of objects may be locked
Data model is based on the real world.
Less code required when applications are object oriented.
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DISADVANTAGES COMPARED TO RDBMS
Lower efficiency when data is simple and relationships are simple.
Relational tables are simpler.
Standards for RDBMS are more stable.
Support for RDBMS is more certain and change is less likely to be required.
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CONCLUSION
Object Oriented Database deals with the complex data or we can say object which are not accessed by any of the database.
Blobs like Videos, Animation and Image.
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REFERENCES
www.cs.sfu.ca/CourseCentral/354/zaiane/material/notes/Chapter9/node13.html
people.cs.pitt.edu/~chang/156/19oodb.html
www.axswave.com/weblibry/relobjdb.htm
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