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Thread: Data Dictionary

  1. #1
    Join Date
    Sep 2003
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    6

    Question Unanswered: Data Dictionary

    Hi all,
    I'm from the DB2 world, new to MySQL, and would like to know about the Data Dictionary. From reading the documentation it looks like the Data Dictionary consists of tables that hold data about the MySQL databases and tables. Is that similar to the system catalog tables in DB2?

    Thanks,

  2. #2
    Join Date
    Sep 2002
    Location
    Montreal, Canada
    Posts
    224
    Provided Answers: 1

    Re: Data Dictionary

    Originally posted by RCAV8OR
    Hi all,
    I'm from the DB2 world, new to MySQL, and would like to know about the Data Dictionary. From reading the documentation it looks like the Data Dictionary consists of tables that hold data about the MySQL databases and tables. Is that similar to the system catalog tables in DB2?

    Thanks,
    No... Not yet at leat but you can extract most of this information through DESCRIBE, SHOW TABLE STATUS, SHOW INDEX and other SHOW statements...

    http://www.mysql.com/doc/en/SHOW.html

    But you won't find that info in a table or a view... Not for now at least...

  3. #3
    Join Date
    Sep 2003
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    6
    Okay, thanks bstjean. The show statements are helpful. But I guess I don't understand what the Data Dictionary tables are used for, if they don't hold the data about the tables/databases that I create.

  4. #4
    Join Date
    Oct 2003
    Location
    Slovakia
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    482
    Originally posted by RCAV8OR
    Okay, thanks bstjean. The show statements are helpful. But I guess I don't understand what the Data Dictionary tables are used for, if they don't hold the data about the tables/databases that I create.
    MySQL has not data dictionary.

  5. #5
    Join Date
    Sep 2003
    Posts
    6

    Question

    Hello ika,
    In the MySQL Manual they talk about the Data Dictionary in:
    http://www.mysql.com/doc/en/Table_and_index.html

    Do you mean that there are no System Catalog tables?

    What are the tables in database MySQL used for?
    mysql> use mysql;
    Database changed
    mysql> show tables;
    +-----------------+
    | Tables_in_mysql |
    +-----------------+
    | columns_priv |
    | db |
    | func |
    | host |
    | tables_priv |
    | user |
    +-----------------+

    When I create a new database a row isn't added to the db table.

  6. #6
    Join Date
    Oct 2003
    Location
    Denver, Colorado
    Posts
    137
    The mysql database is used for permissions. An entry in the db table allows or denies specific permissions to certain users or hosts on the database level. The data dictionary is accessed only by using the SHOW and DESCRIBE syntax.

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