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  1. #1
    Join Date
    Feb 2004

    Unanswered: Need help creating database


    I have been struggling for 2 days with installing Oracle 10g on for Linux. I have extensive experience running MySQL and linux, but none with oracle. I have looked around quite a bit, but with terminology differences from MySQL and even between different versions of Oracle, I have become a little confused. So, I figured that I would ask some experts.

    My first question is in regards to the structure of Oracle. In MySQL you have a database server, then below that any number of databases, then any number of tables in those databases. My question is, could someone explain to me the heirarchy in Oracle? What is the SID? Is it the same as the "global database name"? Do I have to run a copy of oracle for every database that i want to run? Would each database have it's own SID? Or are they one in the same?

    My second question is, when i run "dbca" (or when the installer runs it), I always get "ORA-12154: TNS:could not resolve the connect identifier specifed". it never askes for me to specify the listener to use, but the listener is running. How does it know what listener to use? The listener config asks for a SID and the database creator conplains about the listener. Seems like a catch 22.

    Third, when i create a database, it defaults the SID to the "Global Database Name" when i am typing. Should these be the same?

    If someone could maybe define these terms in a way that a MySQL admin would understand, I would be extremely grateful.

    Thanks in advance

  2. #2
    Join Date
    Jan 2004

    Oracle Fundas

    The architecture of Oracle is huge I think it will be better if u go through the Oracle manuals.
    I can explain the logical hierarchy..
    Data storage starts in Oracle in the form of Oracle Blocks which is the smallest unit of storage. The oracle block comprises of multiple OS blocks. A collection of Orcale blocks makes up an extent. A collection of used extents make up a segment. Segments constitutes a Tablespace.
    A database comprises of one or more Tablespaces.
    Tablespace is a logical thing actually the data are stored in the datafiles associated with a tablespace.A tablespace consists of one or many datafiles but a datafile cannot span accross more than one Tablespace.

    Regarding instance every database has an instance .
    Actually an instance which is a combination of Background Processes and Memory Structures needs to be up which then mounts up the DB.
    U can have more than one database under one installation of ur Oracle S/w.
    SID is nothing but the instance name. There is an Environmental variable called ORACLE_SID.
    I have skipped the Physical architecture which involves
    1.Control files.
    2. Data files.
    3. Redo log files.
    4. Archived Redo log files.
    5. Initialization Parameter file/Sp file.
    6.BAckground Processes.
    Memory Structures:
    which I leave on u to read.
    These are very little excerpts of Oracle DB technology. I know its very difficult to make out from such a small update the versatility of Oracle.
    I have tried to answer ur questions very honestly.If I have missed any one of them do write to me.
    Above all a suggestion would be to go through any document on Oracle architecture.

    Regarding Tnslistener
    U just check the output of lsnrctl stat
    moreover check ur ORACLE_SID is set properly .
    Please Post all the steps u have followed in DB creation and mention the step where u r stuck.
    Happy Exploration ,
    Last edited by kausik_m123; 02-18-04 at 14:36.

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