History of Implementation Data Models

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History of Implementation Data Models
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Databases were

• Early Business Computer Systems
• Accounting functions - payroll, profit/loss
  statements
• Files of data - file oriented (physical hardware)
• sequential and random access (index)

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In 1960's needed

• Integrated centralized data structure
• Redundancy
• DBA's
• Data models

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Mid 1960's - Hierarchical data model

•  logical level - data relationships
• relationships structured as hierarchies
• parents and children
• child can have only 1 parent
• 1-to-many

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Hierarchical Example

• department customer
• Employee project invoice
  store
• dep super worker invoice_line contact

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Hierarchical DB

• Used pointers
• Any query through the data followed pointers
• manipulated 1 row at a time
• how about many-to-many relationships?
• Problems?

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Late 1960's - Network Model

•  many-to-many relationships
•  more than 1 parent
• Owner-Member Relationship
• Instances or Occurrences
•   Problems?

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Network example

• Sales rep customer
• invoice store
• invoice _line contact

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1970's Relational Model - E.F. Codd

•  Rows and Columns
• Instead of 1 record at a time, files or sets at
  a time
• Easier to write queries
• Limitations?

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Relational example

• Customer
• CID storeID contact Invoice
• Sales Rep
• SRID Invoice InvoiceLine

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1980's Object-Oriented DBs

•  Represent real-world entities as objects
• Objects and relationships
• Classes and instances
• Specialization /Generalization
• Inheritance, methods
• Similar to hierarchical
• Most versions based on relational
• Problems?

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1990s Extend Relational

• Object-Relational DBs
• Keep relational, but add OO features
• Additional Issues
• Distributed DBs
• Data mining and data warehouses
• Real-time Databases

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2000s Recent Issues

• Data integration
• Database Security
• Web Databases Information Retrieval
• XML Databases
• Mobile Databases
• Sensor Databases
• Data-intensive computing (Data Grids)
• Cloud computing - where do databases fit in?