SCPT 4: Introduction to File Structures in Database

SCPT 4: Introduction to File Structures in Database


Hello welcome back to your oracle dba tutorial in this tutorial we are going to discus about the files structure so this the abstract picture of oracle database server which is instance plus database files in this short videos we are going to discus about what are different types of database files are exist in a oracle database server so essentially this is the focus and we are going to explain what are different types of oracle database files the first one is parameter file essentially this parameter file tells me how the instance is configured that means how big is the sga or it can tell how many of database processes called db writer a by default it is one we can also start with five db writer so in that case our parameter file will contain those information so essentially whenever during the database start op we use parameter file to configured the instance and the second thing is about data files and this is where all of your data will ultimately be stored that means whenever we are creating a table emp and lets say we are inserting ten rows employ king and clerk and all this things these information are stored in a operating system file and that is called database file and then essentially every database most have at least one data file and this is one of the most important file because this contains all our information then number three is redo lock file ok so redo lock file basically are the transaction locks of the database virtually every operation that u perform on the oracle database generate some amount of redo that means whenever i am doing in delete from emp that means this is a statement i am doing that i am going delete from emp then in the redo lock file we are going to create a transaction saying that employ table is deleted at this amount of time and then lets say we do create a table creatle table x in that case in the redo lock file we are going to put a information that table x is created at this point of time so essential if i look at my redo lock file the redo lock file is going to tell me what kind of operation i am doing and then by using redo lock file i can recover my database at if in case of a media or instance falior all right because redo lock file keep stract of transaction say if i want to replay my redo lets say i have deleted my employ that means i am going to do some insert to the employ table that means this redo lock file must contain all those information so that i can revert back this delete database happens some point of time then the number four file is control file so control file basically contains a directory of all other files for example control file tells the instance where the database and redo lock file are lets say we have a data file called c colon data .dbf and we have a redo lock file called c column redo 1.dbf so in that case the control file will contain all information about where this data files are located where this redo lock files are located and instance is going to read this control file information to see where those data files and is going to open those data files so that we can add data in to those data files and this is one of the most important files and then what we do we want to protect this control file that means instead of just storing one copy we probable going to store four copies of control file in case control file one is got destroyed because of some disk failior or whatever the reason may be then we can revot back to the duplicate control file which is also same as the first file ok so this is called multiplexing of control file all right and the next one is called temp file ok so to cater to the temporary requirement of space we use temp file for example whenever you are giving this select statement called select star from emp order by e name so this an operation where we get the employ table data to some temporary location where we can sorted right so basically whenever we are going to do a sorting operation all this things we need some temporary palce where we just use to short and ones we finished the sorting we don’t need those temporary location and this is why we need a temporary file on the storage structure then the number six is password file all right so the password file are used to authenticate user performing administrative task over a network that means instead of logging into the machine directly if i just connect from another machine over tellnet whatever then i need password file to authenticate the remote user so that he can do administrative work like starting of a database and so on the last file is trace and allot log so as you have seen that we have lot of database background processes for example for whatever reason their is a on like for example their is the back ground processes is terminated abropiate in that case it is going to write something to the trace file so that anybody wants to look at a later point of time can probably diagnose what causes this error or whenever we have Ora 600 or something you know a unexpected error then oracle by default generate some trace file so that later on some body can take a look and figure out what went wrong to the oracle database and the lot log is something that a time stamp base log file which is we say what is going on the oracle database server so these are the basically very overview of database files what we are going to do in our next videos we are going to discus in details about this files

Danny Hutson

19 thoughts on “SCPT 4: Introduction to File Structures in Database

  1. These are really great videos. Can I download them to listen offline? i cant search section 9.
    person recorded these is simple brilliant!

  2. Hi,
    These vedios are very useful especially beginners. Your way of explanation is supertb. May I know your name and contact number ?
    Please upload vedios No.49,51,52 and 53, which are deleted.
    Also, please continue to upload vedios from No. 58
    We are eagar

    Regards
    Bhadram

  3. Thanks for your comments. Please check the Oracle Database Server Concept course at mentorsnet dott org. Even though we put all our videos on Youtube, we highly recommend to use mentorsnet platform.

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