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CS 338 Databases and Database Users INTRODUCTION Bojana Bislimovska Winter 2017 Major research • • • • • • Outline Introduction An example Characteristics of the database approach Actors on the scene Workers behind the scene When not to use a DBMS Major research Data Diversity of Data Major research • Types of available data Text data Multimedia data Data in Social Networks Weather data Scientific data Web data Sensor data Stock data Enterprise data etc. Major research Database • Database logically coherent collection of data with inherent meaning Some aspect of the real world (miniworld) Designed and populated with data for a specific purpose It can be of any size or complexity Database Management System Major research Database Management System (DBMS) General-purpose software system that facilitates the processes of defining, constructing, manipulating and sharing databases among various users and applications. Database Management System Major research • Database Management System (DBMS) General-purpose software system that facilitates the processes of defining, constructing, manipulating and sharing databases among various users and applications. Additional features: • System protection against hardware or software malfunction • Maintenance of a database system over time Database Management System Major research • Database Management System (DBMS) General-purpose software system that facilitates the processes of defining, constructing, manipulating and sharing databases among various users and applications. • DBMS examples IBM’s DB2, Microsoft’s Access and SQL Server, Oracle, MySQL, SAP’s SQL Anywhere DBMS Features Major research • Defining a database Specify data types, structures and constraints Stored in the form of a database catalog Meta-data: information stored inside a catalog • Constructing a database Storing data on a storage medium • Manipulating a database Querying a database to retrieve specific data Update database to reflect miniworld changes DBMS Features Major research • Sharing a database Multiple users and programs access concurrently Application programs access the database • send queries Transaction • An atomic unit of queries and updates that must be executed as a whole Database System Major research Database and DBMS software => Database system Major research Example Restaurant database File Processing Major research • Used in pre-DBMS databases • Each user defines and implements the files needed for a specific software application • Data definition is part of the application programming • Change of records structure requires change of file access programs • As the application base grows many shared files a multitude of file structures a need to exchange data among applications Characteristics of the Database Major research Approach • Database approach Self-describing nature of a database system • Description of database structure => Catalog Insulation between programs and data, and data abstraction • Conceptual representation of data (data model) • Storage and implementation details hidden Support of multiple views of data for different user types Sharing data and multiuser transaction processing • Concurrency control of DBMS => correct execution of transactions Actors on the Scene Major research • Database Administrators Authorize access to the database (DB) Coordinate and monitor its use Acquire software and hardware resources as needed • Database Designers Understand requirements of database users Identify data to be stored in the DB Choose appropriate structures to represent the data Actors on the Scene Major research • End Users Require access for querying, updating and generating reports Casual end users • Use sophisticated query interface • Occassionaly access the DB, may ask different information each time Naive or parametric end users • Constant query and update of the DB (canned transactions) • e.g. Available through mobile apps Sophisticated End Users • Familiarize with the DBMS features to implement their own applications with specific requirements Actors on the Scene Major research • End users Standalone Users • Maintain personal databases by using ready-made program packages which inlcude menu and graphic-based interfaces • System analysts Determine requirements of end users to develop specifications for canned transactions • Application programmers Implement these specifications as programs, maintain the canned transactions Workers behind the Scene Major research • DBMS system designers and implementers Design and implement the DBMS modules and interfaces as a software package • Tool developers Design and implement tools that facilitate database modeling and design, database system design • Operators and maintenance personnel Responsible for hardware and software environment running and maintenance (for the DB system) When Not to Use a DBMS Major research • When there exist high overhead costs of using a DBMS • Customized database applications are more desirable in the following cases: Simple, well-defined database applications are not expected to change at all Stringent, real-time requirements for some applications may not be met (reason: DBMS overhead) No multiple users access to data Embedded systems with limited storage capacity (DBMS would not fit) • Examples CAD tools, GIS, communication and switching systems