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Thread: Data Modelling

  1. #1
    Join Date
    Jun 2014
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    Data Modelling

    Hello there,

    Data can be modelled at logical level and physical level.After logical design ie ER Model ,we convert it to physical model ie Tables. . Tables are created in case of RDBMS. But the data is not actually stored as TABLES on the disk.It is yet again a way to represent the day for processing. Then how is the data actually stored ? Is it the responsibility of the DBMS alone, to define the storage structures ? How does this work ?

    Thanks in Advance.

  2. #2
    Join Date
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    Data storage depends on the platform.
    Responsibilities are delegated by the engine and the platform.
    Not usually.
    How it works depends on the platform.

    Unless a VERY specific platform is given, these are Masters or PhD level essay questions.

    -PatP
    In theory, theory and practice are identical. In practice, theory and practice are unrelated.

  3. #3
    Join Date
    Jun 2014
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    Platform specific ?

    Hello Pat Phelan,

    Thank you for the reply.

    Read that you are expert in databases and specifically data modelling !

    To get a clearer picture,given a platform(take any platform ) could you please explain how it works in that ?

  4. #4
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    Probably the most commonly used engine with the most external documentation is Microsoft SQL Server. You can find many (hundreds or thousands) of pages in the blog of Paul Randal describing how the engine works, how the data is stored, and how the responsibilities are delegated.

    If you would prefer an open source database engine, there is good documentation for PostgreSQL that is included with their product documentation. This may be a bit drier reading, but having access to the source code helps a great deal when you have specific questions.

    I can't really recommend other database engines, but you might have better luck with them than I have had. I would advise against desktop tools like dBase, Access, FileMaker, etc. because those are built to run on a client desktop so they use almost polarically opposite design patterns. MariaDb or its predecessor MySQL haven't been easy for me to understand because they support so many different ways for storing data, but you might have better luck. There is some good documentation for other commercial products like Sybase ASE, Oracle, and DB2 but those take a fair bit of hunting to find and a relatively large amount of work to understand.

    -PatP
    In theory, theory and practice are identical. In practice, theory and practice are unrelated.

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