lec1.pptx

Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe  CHAPTER 1 Databases and Database Users Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 2 Types of Databases and Database Applications Traditional Applications: Numeric a...

Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe  CHAPTER 1 Databases and Database Users Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 2 Types of Databases and Database Applications Traditional Applications: Numeric and Textual Databases More Recent Applications: Multimedia Databases Geographic Information Systems (GIS) Biological and Genome Databases Data Warehouses Mobile databases Real-time and Active Databases Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 3 Recent Developments (1) Social Networks started capturing a lot of information about people and about communications among people-posts, tweets, photos, videos in systems such as: - Facebook - Twitter - Linked-In All of the above constitutes data Search Engines- Google, Bing, Yahoo : collect their own repository of web pages for searching purposes. Slide 1- 4 Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Recent Developments (2) New Technologies are emerging from the so- called non-database software vendors to manage vast amounts of data generated on the web: Big Data storage systems NOSQL (Not Only SQL) systems A large amount of data now resides on the “cloud” which means it is in huge data centers using thousands of machines. Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 5 Basic Definitions Database: A collection of related data. Data: Known facts that can be recorded and have an implicit meaning. Mini-world: Some part of the real world about which data is stored in a database. For example, student grades and transcripts at a university. Database Management System (DBMS): A software package/ system to facilitate the creation and maintenance of a computerized database. Database System: The DBMS software together with the data itself. Sometimes, the applications are also included. Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 6 Impact of Databases and Database Technology Businesses: Banking, Insurance, Retail, Transportation, Healthcare, Manufacturing Service Industries: Financial, Real-estate, Legal, Electronic Commerce, Small businesses Education: Resources for content and Delivery More recently: Social Networks, Environmental and Scientific Applications, Medicine and Genetics Personalized Applications: based on smart mobile devices Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 7 Simplified database system environment Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 8 Typical DBMS Functionality Define a particular database in terms of its data types, structures, and constraints Construct or Load the initial database contents on a secondary storage medium Manipulating the database: Retrieval: Querying, generating reports Modification: Insertions, deletions and updates to its content Accessing the database through Web applications Processing and Sharing by a set of concurrent users and application programs – yet, keeping all data valid and consistent Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 9 Application Activities Against a Database Applications interact with a database by generating - Queries: that access different parts of data and formulate the result of a request - Transactions: that may read some data and “update” certain values or generate new data and store that in the database Applications must not allow unauthorized users to access data Applications must keep up with changing user requirements against the database Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 10 Additional DBMS Functionality DBMS may additionally provide: Protection or Security measures to prevent unauthorized access “Active” processing to take internal actions on data Presentation and Visualization of data Maintenance of the database and associated programs over the lifetime of the database application Called database, software, and system maintenance Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 11 Example of a Database (with a Conceptual Data Model) Mini-world for the example: Part of a UNIVERSITY environment. Some mini-world entities: STUDENTs COURSEs SECTIONs (of COURSEs) (academic) DEPARTMENTs INSTRUCTORs Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 12 Example of a Database (with a Conceptual Data Model) Some mini-world relationships: SECTIONs are of specific COURSEs STUDENTs take SECTIONs COURSEs have prerequisite COURSEs INSTRUCTORs teach SECTIONs COURSEs are offered by DEPARTMENTs STUDENTs major in DEPARTMENTs Note: The above entities and relationships are typically expressed in a conceptual data model, such as the ENTITY-RELATIONSHIP data model (see Chapters 3, 4) Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 13 Example of a simple database Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 14 Main Characteristics of the Database Approach Self-describing nature of a database system: A DBMS catalog stores the description of a particular database (e.g. data structures, types, and constraints) The description is called meta-data*. This allows the DBMS software to work with different database applications. Insulation between programs and data: Called program-data independence. Allows changing data structures and storage organization without having to change the DBMS access programs. Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 15 Example of a simplified database catalog Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 16 Main Characteristics of the Database Approach (continued) Data Abstraction: A data model is used to hide storage details and present the users with a conceptual view of the database. Programs refer to the data model constructs rather than data storage details Support of multiple views of the data: Each user may see a different view of the database, which describes only the data of interest to that user. Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 17 Main Characteristics of the Database Approach (continued) Sharing of data and multi-user transaction processing: Allowing a set of concurrent users to retrieve from and to update the database. Concurrency control within the DBMS guarantees that each transaction is correctly executed or aborted Recovery subsystem ensures each completed transaction has its effect permanently recorded in the database OLTP (Online Transaction Processing) is a major part of database applications. This allows hundreds of concurrent transactions to execute per second. Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 18 Database Users Users may be divided into “Actors on the Scene”: Those who are involved in the design, use and maintenance of a large DB with hundreds or thousands of users “Workers Behind the Scene”: Those who work to maintain the DB system but who are not actively interested in the DB content as part of their daily job Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 19 Database Users – Actors on the Scene Actors on the scene Database administrators: Responsible for authorizing access to the database, for coordinating and monitoring its use, acquiring software and hardware resources, controlling its use and monitoring efficiency of operations. Database Designers: Responsible to define the content, the structure, the constraints, and functions or transactions against the database. They must communicate with the end- users and understand their needs. Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 20 Database End Users Actors on the scene (continued) End-users: They use the data for queries, reports and some of them update the database content. Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 21 Database Users – Actors on the Scene (continued) System Analysts and Application Developers System Analysts: They understand the user requirements of naïve and sophisticated users and design applications to meet those requirements. Application Programmers: Implement the specifications developed by analysts and test and debug them before deployment. Business Analysts: There is an increasing need for such people who can analyze vast amounts of business data and real-time data (“Big Data”) for better decision making related to planning, advertising, marketing etc. Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 22 Database Users – Workers behind the Scene System Designers and Implementors: Design and implement DBMS packages in the form of modules and interfaces and test and debug them. The DBMS must interface with applications, language compilers, operating system components, etc. Tool Developers: Design and implement software systems called tools for modeling and designing databases, performance monitoring, prototyping, test data generation, user interface creation, simulation etc. that facilitate building of applications and allow using database effectively. Operators and Maintenance Personnel: They manage the actual running and maintenance of the database system hardware and software environment. Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 23 Advantages of Using the DBMS Approach Controlling redundancy in data storage and in development and maintenance efforts. Sharing of data among multiple users. Restricting unauthorized access to data. Only the DBA staff uses privileged commands and facilities. Providing persistent storage for program Objects. Providing Storage Structures (e.g. indexes) for efficient Query Processing Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 24 Advantages of Using the Database Approach (continued) Providing optimization of queries for efficient processing based on storage structure. Providing backup and recovery services in case of failures. Providing multiple interfaces to different classes of users. Representing complex relationships among data. Enforcing integrity constraints on the database. Drawing inferences and actions from the stored data. Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 25 Additional Implications of Using the Database Approach Potential for enforcing standards: This is very crucial for the success of database applications in large organizations. Standards refer to data item names, display formats, screens, report structures, meta-data (description of data), Web page layouts, etc. Reduced application development time: Incremental time to add each new application is reduced. Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 26 Additional Implications of Using the Database Approach (continued) Flexibility to change data structures: Database structure may evolve as new requirements are defined. Availability of current information: Extremely important for on-line transaction systems such as shopping, airline, hotel, car reservations. Economies of scale: Wasteful overlap of resources and personnel can be avoided. Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 27 Historical Development of Database Technology Early Database Applications: The Hierarchical and Network Models were introduced in mid 1960s and dominated during the seventies. Relational Model based Systems: Relational model was originally introduced in 1970, was heavily researched and experimented within IBM Research and several universities. Relational DBMS Products emerged in the early 1980s. Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 28 When not to use a DBMS Main inhibitors (costs) of using a DBMS: High initial investment and possible need for additional hardware. Overhead for providing generality, security, concurrency control, recovery, and integrity functions. When a DBMS may be unnecessary: If the database and applications are simple, well defined, and not expected to change. If access to data by multiple users is not required. When a DBMS may be infeasible: In embedded systems where a general purpose DBMS may not fit in available storage Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 29 Chapter Summary Basic Definitions of database, data, DBMS Typical DBMS Functionality Main Characteristics of the Database Approach Types of Database Users Advantages of Using the Database Approach Historical Development of Database Technology Extending Database Capabilities When Not to Use Databases Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 30