Database Planning

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  • Resource: an asset that has value and incurs cost Resources include capital equipment, financial assets, personnel and data Database is a resource because Operational data has value Database incurs cost Professionally managed by DBA
  • Data: raw facts Example: printout of tables as they are stored Information: processed data, useful for decision-making Example: formatted report using database
  • Enterprise organization for which the database is designed Cannot observe reality and make decisions Mini-world , or Universe of Discourse – part of the world that is represented in the database
  • Metadata – data about data For each entity set there is a record type Data item types are columns in table data item smallest named unit (field – set of adjacent bytes – more physical meaning) Data aggregate – grouping of data items (for an address) Data dictionary – system catalog – in addition to storing all info mentioned above, they can be used for database accesses File (data set) collection of record occurances
  • Data sublanguage allow non-embedded or interactive commands for access to database ( DDL ) - used to define the database ( DML ) - is used to process the database – used to generate reports
  • Systems analysis approach to design assumes every system has a lifecycle , and will eventually be replaced Staged database design centers on first developing a conceptual model that evolves and survives
  • Faithfully mirrors the operations of the organization Flexible enough to allow changes as new information needs arise Supports many different user views Independent of physical implementation Does not depend on the model used by a particular database management system
  • Analyze user environment – studies present applications – inputs and outputs, reports and use of system – identify all needs (present and future) Develop conceptual data model – identifies entities, attributes, and relationships (applications and transactions, kinds of access, volume of transactions and data, frequency of access Choose a DBMS – impose restrictions – must satisfy environment Develop logical model, by mapping conceptual model to DBMS – maps conceptual model to chosen DBMS Develop physical model – plans the layout of the data – multiplexing (write to two separate locations at the same time) Evaluate physical model – estimate performance of all applications and transactions – develop a prototype to validate user views Perform tuning, if indicated – modify physical structure or optimize software Implement physical model Arrows show were there is feedback and opportunities to change
  • CASE (Computer-Aided Software Engineering) tools Upper case : used for collecting and designing data, designing logical model, designing applications Lower case : used for implementing the database, including prototyping, data conversion, generating application code, generating reports, testing Data dictionary Project management software
  • Collecting information about data in central location Securing agreement on meanings of items Identifying inconsistencies – synonyms and homonyms Keeping track of changes to DB structure Recording external/logical/physical models & mappings Recording access control information Providing audit information
  • Database Planning

    1. 1. Announcements <ul><li>Homework 1 Due 9/15 </li></ul><ul><li>Project: Step 1 Due 9/17 </li></ul><ul><li>Reading for Wednesday </li></ul><ul><ul><li>2.6 – 2.8 </li></ul></ul>
    2. 2. Database Planning Lecture 3
    3. 3. Data as a Resource <ul><li>Resource: </li></ul><ul><li>Resource Examples: </li></ul><ul><li>Why is a database is a resource? </li></ul>
    4. 4. Characteristics of Data <ul><li>Data vs. information </li></ul><ul><ul><li>Data: </li></ul></ul><ul><ul><ul><li>Example: </li></ul></ul></ul><ul><ul><li>Information: </li></ul></ul><ul><ul><ul><li>Example: </li></ul></ul></ul>
    5. 5. Four Levels of Data <ul><li>Real world </li></ul><ul><ul><li>Enterprise </li></ul></ul><ul><ul><li>Mini-world , or Universe of Discourse </li></ul></ul><ul><li>Conceptual Model </li></ul><ul><ul><li>Entities </li></ul></ul><ul><ul><li>Entity sets </li></ul></ul><ul><ul><li>Attributes </li></ul></ul><ul><ul><li>Relationships </li></ul></ul>
    6. 6. Four Levels of Data <ul><li>Logical model of database </li></ul><ul><ul><li>Metadata </li></ul></ul><ul><ul><li>Record types, data item types, data aggregates </li></ul></ul><ul><ul><li>Stored in data dictionary </li></ul></ul><ul><li>Data occurrences </li></ul><ul><ul><li>Database itself </li></ul></ul><ul><ul><li>Data instances </li></ul></ul><ul><ul><li>files </li></ul></ul>
    7. 7. Data Sublanguages <ul><li>Languages </li></ul><ul><ul><li>DDL </li></ul></ul><ul><ul><li>DML </li></ul></ul><ul><li>Host Language </li></ul>
    8. 8. Staged Database Design <ul><li>Systems analysis </li></ul><ul><li>Staged database design </li></ul>
    9. 9. Characteristics of a Conceptual Database Model
    10. 10. Stages in Database Design Analyze User Environment Develop Conceptual Model Choose DBMS Develop Logical Model Develop Physical Model Evaluate Physical Model Tune System Implement System
    11. 11. Design Tools <ul><li>CASE </li></ul><ul><ul><li>Upper case : </li></ul></ul><ul><ul><li>Lower case : </li></ul></ul><ul><li>Data dictionary </li></ul><ul><li>Project management software </li></ul>
    12. 12. Data Dictionary <ul><li>Contains metadata </li></ul><ul><li>Can be integrated (part of DBMS) or free-standing </li></ul><ul><li>Useful for </li></ul>
    13. 13. Project Management Software <ul><li>Tools to help plan and manage projects, especially those with many people </li></ul><ul><li>Include several types of charts and graphs </li></ul><ul><ul><li>GANTT chart- See Figure 2.12 </li></ul></ul><ul><ul><li>PERT chart </li></ul></ul><ul><li>User specifies </li></ul><ul><ul><li>Scope and objectives </li></ul></ul><ul><ul><li>Major tasks and phases </li></ul></ul><ul><ul><li>Task dependencies </li></ul></ul><ul><ul><li>Resources, including personnel </li></ul></ul><ul><ul><li>Timelines </li></ul></ul><ul><li>Software can </li></ul><ul><ul><li>Generate calendars </li></ul></ul><ul><ul><li>Produce graphs with different views of project </li></ul></ul><ul><ul><li>Provide means of communication for staff </li></ul></ul>
    14. 14. Database Administrator Skills <ul><ul><li>DBA must be </li></ul></ul><ul><ul><ul><li>Technically competent </li></ul></ul></ul><ul><ul><ul><li>Good manager </li></ul></ul></ul><ul><ul><ul><li>Have excellent interpersonal and communication skills </li></ul></ul></ul><ul><ul><li>Has primary responsibility for planning, designing, developing and managing the operating database </li></ul></ul><ul><ul><li>Database designer may do conceptual and logical design; DBA does physical design, implementation, develops, manages system </li></ul></ul>
    15. 15. Planning and Design Stage <ul><ul><li>Preliminary planning </li></ul></ul><ul><ul><li>Identifying user requirements </li></ul></ul><ul><ul><li>Developing and maintaining the data dictionary </li></ul></ul><ul><ul><li>Designing the conceptual model </li></ul></ul><ul><ul><li>Choosing a DBMS </li></ul></ul><ul><ul><li>Developing the logical model </li></ul></ul><ul><ul><li>Developing the physical model </li></ul></ul>
    16. 16. Development Phase <ul><ul><li>Creating and loading the database </li></ul></ul><ul><ul><li>Developing user views </li></ul></ul><ul><ul><li>Writing and maintaining documentation </li></ul></ul><ul><ul><li>Developing and enforcing data standards </li></ul></ul><ul><ul><li>Developing and enforcing application program standards </li></ul></ul><ul><ul><li>Developing operating procedures </li></ul></ul><ul><ul><li>Doing user training </li></ul></ul>
    17. 17. Database Management Phase <ul><li>Monitoring performance </li></ul><ul><li>Tuning and reorganizing </li></ul><ul><li>Keeping current on database improvements </li></ul>

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