How oracle finds the locatoin of data ?
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Thread: How oracle finds the locatoin of data ?

  1. #1
    Join Date
    Feb 2002
    Posts
    267

    How oracle finds the locatoin of data ?

    hi,

    Whenever i issue a query like

    sql>select * from emp where empno=25;

    How does oracle go about in getting the locations
    of the datafile, and segment number in order to retrieve the data.

    Which all dictionary table does Oracle need to query
    to reach to the table data.

    In this scenario what are the roles of the dictionary tables
    obj$, fet$, tab$ and seg$.
    In which order does oracle query these tables to reach the
    exact location of the data ?

    regards
    sonia

  2. #2
    Join Date
    Jan 2001
    Posts
    2,828
    Hi

    well you need to set up tracing for that something like this

    create or replace trigger sql_trace after logon on database
    begin
    if ( user = 'SONIA' )
    then
    execute immediate 'alter session set events ''10046 trace name context forever, level 12';
    end if;
    end;

    grant alter session to sonia


    then login and logout

    and
    conn as sonia/your_password

    select empno from emp where empno=12

    then exit

    Now go to userdump test and have a look at the trace file you will have everything.

    i would have posted the results here but for ora 600 errors i am getting as i need to apply some patches ..

    regards
    Hrishy

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