Databases and Data Warehouses - Information System - Lecture Slides, Slides of Information Systems

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Databases and Data Warehouses

Information Granularity

 Refers to the level of detail of information  Detailed (POS transaction)  Course (Global sales totals)

Transactional vs. Analytical

Information

Information Dimensions

 Information timeliness

 Obsolete information is useless  Today’s information needs to be provided in real time or near real time

 Information quality

 Wrong information is useless  Redundant information can be the cause of errors  Information must be complete

Database Vendors

 The industry has consolidated

 IBM

 DB2 Universal

 Oracle

 Microsoft  SQL Server  Access

 Sun (MySQL)

 Is now Oracle

Database Performance

 Transaction Processing Performance Council provides standard benchmarks

 TPC-C – Online transaction processing

 TPC-E – Online brokerage transactions

 TPC-H – Ad-hoc decision support

 TPC-W – Web / E-commerce

1960s Data Management

 These are legacy systems  Batch processing  Characterized by traditional file processing  Data processing was sequential  Not possible to directly locate a particular file record  Data dependent on the programs that used the data  Program data dependence

1970s Data Management

 Batch processing gives way to on line transaction processing  Files stored on disk rather than tape  Any record can be located in the same amount of time  Technologies  Indexed Sequential Access Method (ISAM)  Virtual Sequential Access Method (VSAM)  Direct Access files  Use a hashing function to derive record keys

1990s Data Management

 Huge data stores and transaction processing capabilities

 Distributed databases

 Object-oriented databases

 6 Million+ transactions per second

Realities of a DBMS

 Data centric rather than application centric  Can be a repository for all an organization’s data  Databases tend to be centralized  Queries get data from a DBMS  SQL is the standard query language  Report generators create printed and Web- based reports  Applications interface with DBMS

Elements of a Database

 Logical view and physical view

 Users see and work with the logical view  Physical view is controlled by the database management system itself

Entities and Attributes

 Relational databases store information in tables (entities)  Customer / order / product

 Tables contain fields (attributes)

 Customer name, address

Database Interaction

Advantages of an RDMS

(Scalability)

 Database can scale to the terabyte or petabyte range  NSA maintains 1.9 trillion telephone call records

 Large databases can span several servers and storage devices