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Database Design

Database Design Steps. Conceptual DesignDefining the projectEstablishing the methodologyGathering the informationLogical DesignProducing the database documentationPhysical DesignCreating and testing the database. Conceptual Design Goals. Scope the projectEstablish goalsEstablish limitsHard

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Database Design

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    1. Database Design Design and Documentation

    2. Database Design Steps Conceptual Design Defining the project Establishing the methodology Gathering the information Logical Design Producing the database documentation Physical Design Creating and testing the database

    3. Conceptual Design Goals Scope the project Establish goals Establish limits Hardware Software Evaluate resources People Existing documentation

    4. Laying the Groundwork Set Project Standards and Guidelines Select a design methodology Define documentation standards for: ERD symbols and naming conventions Transaction Analysis sheets Metadata Dictionary

    5. Database Design Documentation Metadata Dictionary Transaction Analysis sheets Database ERD CRUD diagram

    6. Metadata Dictionary What is the Metadata Dictionary? A “living document” Contains “all information” on the project “One-stop shopping” place for information Repository and clearing house for all information

    7. Conceptual Design What is IN the Metadata Dictionary? Project Standards and Guidelines Statement of goals and scope Design methodologies used As they are uncovered include: List of the known Business Rules Terms, definitions and formulas

    8. Conceptual Design Eventually the Metadata Dictionary will include: “Always current” database ERD CRUD diagram Detailed transaction sheets Table/column definitions and datatypes A table of contents and index for the MDD

    9. Gather Project Information Examine existing system Training Manuals Interviews Determine key decision makers Determine knowledgeable (accurate) sources Determine receptive (accessible) sources Observation Determine enhancements Incorporate new project goals

    10. Starting the Metadata Dictionary Establish and collect Business Rules Document the rule, the date and the source Organize the business rules appropriately into the metadata dictionary Document the business “workflow” DFDs, Workflow diagrams, Use Cases

    11. Starting the Logical Design Phase Input: Project goals Business work flow Business rules Output: Well documented Database design Used as a blueprint for Physical Design

    12. ERD and Transaction Sheets Once the business “workflow” is established: Start a “rough” ERD Use Normalization techniques based on the business rules Start “rough” Transaction Analysis sheets

    13. Transaction Analysis documentation For each Business Function uncovered, start a “rough” transaction analysis sheet. Document the transaction as best as possible As the ERD evolves, evolve the transactions as well Some initial transactions may be split and others may be combined depending on business needs

    14. What information should a Transaction Analysis have? Identifier A number and short name, Full verbal description Detailed “transaction code” description Relevant data Time of day, priority, frequency, security issue and user access List of affected tables Pertinent business rules necessary to understand the transaction

    15. A “CRUD” diagram CRUD stands for: Create Read Update Delete Merges the database design (as shown in the ERD) and the business functions/transactions

    16. Purpose of the CRUD The CRUD diagram will show on one sheet: All transactions and the tables they interact with Potential locking conflicts between transactions Table activity

    17. Using the CRUD, ERD and TA sheets the DBA can... Estimate, eliminate or minimize potential locking conflicts Prioritize or maximize disk I/O throughput utilization Estimate correct indexing strategies Establish database security

    18. What’s left? Table Analysis Assessing initial table disk sizes and future growth potential and file placement Assessing table structures and indexing options Table/Index maintenance plans Logical guesses can be made from the ERD, TAs and CRUD

    19. Documentation Resources and Depth? Fit the documentation to the project Small designs: Spiral notebook and folders Larger designs: On-line documentation and files Large “Mission Critical” systems: Perhaps a separate database to store the documentation Full-time “librarian” to maintain the documentation

    20. The End

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