Database Users and Administration
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Database Users and Administration

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  • INTRODUCTION You will already have gathered that the DBMS is a complex entity. While it is meant to facilitate the operation of a business or orgnisation, it needs considerable care and attention lavished on it. If an enterprise depends upon its data then the repositiry and guardian of that data (the database and its DBMS) needs the sort of coddling that you would give an elderly reletive who might be persuaded to leave you a fortune. The people who are generally delegated to perform this task are known as database administration staff. In a small company this may comprise of one person, in a large organisation it may constitute a department in its own right. Whatever the staffing situation it is an extremely important function.
  • Today we will look at the different types of database user. We will look at the differences between data administration and database administration - a very important distinction. We will then concentrate on database Administration and its functions along with the role of a database administrator.
  • There are a number of different types of people who use database, and what they can/want to do is different. The end user is the person who, at the end of the day, uses the information that is available in a database for a business purpose. For example, it is the end user, who might want to insert a customer record, or to type in an order. The non technical end user usually has no knowledge of the background processes that go on when a database is being used. For example they do not know that when they insert a record a piece of code is called which validates their input and which perhaps uses SQL to update the database, which in turn is using the RDMS etc.) The end users expertise is in the use of the data. Usually they know the application from the business side of things. They understand the data and how it is used. They should NEVER be underestimated because of their non technical knowledge!
  • The information available to an end user should always be: CORRECT There should never be inconsistent, or out of date information READILY AVAILABLE The user should be able to use the information whenever they need to. It would be no use if the user could only use the system for half of the time USER FRIENDLY FORMAT The design of the database should be such that an end user finds it easy to use. For example, it should always be clear to a user where they are in the system, what data they should enter. If they make a mistake they should be able to correct it easily. Screens should be easy to use, and well laid out etc. MEET THEIR REQUIREMENTS This is essential. If a database only does half of the things a user requires then they will not use it! For example, if you had a student administration system which could not record a coursework and exam mark - only a module mark, then it would not be very useful for those modules which used both!!!!In this case a Module Leader would not use this system because it would not do what they wanted. ALLOW THEM TO BE PRODUCTIVE A database is of no use if a user cannot do their work! They must be able to use it and to not get held up unnecessarily.
  • The next type of user of a database is a database specialist. The functions suggested by these job titles may well be performed by a smaller number of people, indeed by only one person. The size of staff in a specialist database function may well depend on the size of the enterprise the complexity of the appplication to be run the complexity of the DBMS chosen the level of the user’s sophistication the phase of the database project
  • It is important to distinguish between data administration and database administration. Data administration is a high level function that is responsible for the overall management of data resources in an organisation , including maintaining corporate wide definitions and standards. It is not the same as Database administration.
  • Database Administration is usually a work group within an organisation’s data processing or management information systems function. The term ‘DBA’ can mean both ‘Data Base Administrator and Database Administration A database is a shared resource & this is a key to understanding the role & importance of the database administrator. The DBA role is mainly one of management and co-ordination. However the scope of DBA functions depends on the position of the DBA in the organisation. Typical functions include: Database planning & design (Development of a strategic plan for database development, defining requirements etc). Database implementation (Creation of database, populating it with data etc). Database protection (security issues, such as back up and recovery). Database Performance (monitoring performance etc)
  • ADMINISTRATION & MANAGEMENT OF DATA CONTENT What data should we hold ADMINISTRATION OF DATA STRUCTURE How should we hold it ADMINISTRATION OF PHYSICAL DATABASE Where should we hold it.
  • Data Content What should we hold? This is concerned with (a) What data should we hold on the database (b) Which users should have access to the database. E.G. Should we allow someone in Personnel to have access to accounting information? Clearly we would not want sensitive data to be accessed by inappropriate people. (c) What levels of access should be given to those users, e.g. Some users may only need access to some transactions. Managers may only need access to summary reports etc. (d) Consistency checks. For example we may need to ensure that if a user enters a value for credit that it doesn’t exceed credit limit etc. (e) Removal of data. How long do we need to keep data for. Do we want to remove details of an order as soon as it has been fulfilled? Do we need to keep exam results for 2 years , 5 years, ten years? Etc
  • STRUCTURE (How do we hold data) (a) How many logical databases do we need - one for each user? How many tables do we need etc (b) What is the table structure ? Normalisation . How many levels of normalisation do we need to go to, 3? or 5? Functional Analysis . Main requirements of the system, what functions are required. E.g. Sales Order Processing - we might need create order amend order delete order You need to think about how the system is going to work De normalisation . The merging of entities back together. Can be done for performance purposes. (c) Security - How will it be implemented. Could be passwords. Could be access to rooms etc.
  • How are consistency checks made? Could be via range checks and data validation. How is access to be optimised? Transactions. You would have forms for major transactions. For example a Query form for payments, and Insert form for Payments etc Clustering. Storage in an optimal way by storing tables physically close to each other on a disk. Indexing. Data sorted in a particular way to make searches for data more efficient. Query Optimisation. You could look at SQL queries. When selecting from several tables at once the order of the tables makes a difference to performance. The table that has the smallest number of matches or joins should be specified last. This reduces the number of table accesses. The order of the select columns should match the order of the order by clause to optimise use of the temporary table. How and when to reorganise the database
  • PHYSICAL DATABASE How many copies should run ? This may depend on the size of the machine you are using, or on the performance of the operating system . When should backups be taken Db files Recovery log files
  • Start Up and Shut down DBMS Parameters. Defaults - how many buffers should be used, e.g. for recover. How many transactions should be held in a buffer before commiting to the database? This may depend on the number of users, on the amount of RAM etc. Control procedures. This may depend on the DBMS. For example what kind of recovery is being used. Recovery logs etc System Failures Export/Import Procedures Rollforward/Rollback.
  • These are the roles that the DBA should carry out in order to successfully administer a database system. - Integrity and consistency - keeping the data error free and consistent from the outset helps to reduce problems in the future - monitoring and tuning - it may be necessary in the future to tune the database to improve performance, so the DBA can use tools to monitor performance - reduce redundant storage - arching data, etc. - sharing of data - again to reduce rendundancy, and ensure that everybody who needs access does have access - security - ensuring the system is secure. - backups - in case there are errors or security problems - recovery - being able to recover using backups and other solutions - discussed in a later lecture - keep down time to a minimum - making sure that any down time is at a convenient time
  • DBA has to liaise with all users of the system. He/she liases with management to ensure the database matches the enterprise objectives, that if there are time/budget constraints then these are achievable, that any future plans are taken into account when designing the system, and that as the organisation changes the database systems changes to keep up
  • These are the roles in liasing with users.
  • These are the roles in liaising with application development staff
  • These are the roles in liasing with operations/technical staff
  • These are the roles in liaising with software vendors
  • These are the roles for hardware vendors

Database Users and Administration Database Users and Administration Presentation Transcript

  • Database Users & Administration
    • Database Users
    • Data Administration
    • Database Administration
    • DBA Functions
    • DBA Role
    Database Users & Administration
    • 1. The End User
    • The one who will use the information
    • Unaware of the background processes
    • Perhaps has little or no computing knowledge
    • Expertise is in the use of the data
    Database Users
    • 1. The End User (cont.)
    • The information must be
      • correct
      • readily available
      • user friendly format
      • meet their requirements
      • allow them to be productive
    Database Users
    • 2. Database specialist
      • Database Administrator
      • Database Designer
      • Database Analyst
      • Database Programmer
      • Database Technician
    Database Users
    • A high level management function(E.g. Director)
    • Determination of overall information needs from a management perspective
    • Developing & administering the policies, procedures, practices & plans for definition, organisation, protection & efficient utilisation of data
    • Encompasses all corporate data whether computerised or not
    Data Administration
    • Normally responsible for computerised systems only
    • Management & Co-ordination function
    • Technical function responsible for:
      • physical database design
      • security
      • backup
      • recovery
      • performance
    Database Administration
    • What is it?
    • “ To successfully set up and manage an environment in which the data resource is effectively used”
    Database Administration
    • THERE ARE THREE MAIN FUNCTIONS:
    • 1 . Administration & management of Data Content
    • 2. Administration & management of Data Structure
    • 3. Administration & management of the Physical Database
    DBA Functions
    • 1. Administration & management of Data Content
      • which data is to be held on the database
      • which users have what kind of access to the database
      • which kind of users have access to individual items of data
      • which consistency checks must be maintained
      • when should data be removed
    DBA Functions
    • 2. The administration and management of data structure.
      • how many logical databases do we need ?
      • what is the table column structure ?
        • normalisation
        • functional analysis
        • de normalisation
      • how is security to be implemented ?
    DBA Functions
    • 2. The administration and management of data structure (Cont.)
      • how are consistency checks made ?
      • how is access to be optimised ?
        • transactions
        • clustering
        • indexing
        • query optimisation
      • how and when to re-organise the database ?
    DBA Functions
    • 3. The administration and management of the physical database
      • how many copies should run ?
        • machine sizing
        • operating system performance
      • when and how should we perform backups?
        • database files
        • recovery log files
    DBA Functions
    • 3.The administration and management of the physical database ( cont.)
      • start-up and shutdown procedures .
        • DBMS parameters
        • control procedures
      • what procedures are required to recover from system failures ?
        • export / import procedures
        • roll forward / rollback
    DBA Functions
    • integrity and consistency
    • monitoring and tuning
    • reducing redundant storage
    • facilitating sharing of data
    • security
    • backups
    • recovery
    • keep down time to a minimum
    DBA Role
    • Liaison with:
    • Management
      • enterprise objectives
      • time constraints for development
      • budget constraints
      • Future plans
      • organisational changes
    DBA Role
    • Liaison with:
    • Users
      • data requirements
      • application priorities
      • ownership of data
      • archiving requirements
      • documentation
      • response times
    DBA Role
    • Liaison with:
    • Application Development Staff
      • security/privacy controls
      • education/training
      • data integrity rules
      • housekeeping programs
      • information about the database
      • Test plans etc.
    DBA Role
    • Liaison with:
    • Operations Staff
      • availability requirements
      • batch job priorities
      • security procedures
      • error recovery requirements
      • performance monitoring etc.
    DBA Role
    • Liaison with:
    • Software Vendors
      • Education/training needs
      • Hardware requirements
      • documentation
      • service support & maintenance
      • utilities etc.
    DBA Role
    • Liaison with:
    • Hardware Vendors
      • hardware capabilities
      • expansion capability
      • incompatibility with any existing hardware
      • servicing requirements
      • training
      • equipment failure
    DBA Role
  • Further Reading
    • Database Administration
      • Connelly & Begg, chapter 4, section 4.7
      • McFadden & Hoffer, chapter 13
    • Next week
      • Database Security, Integrity and Recovery