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  1. #1
    Join Date
    Apr 2010
    Posts
    1

    Question Unanswered: Oracle to MYSQL conversion

    Hi All,


    we are migrating the DB from Oracle to MYSQL conversion .

    Can anyone involved before this kind of project?
    Can we move all objects to MYSQL?
    Can we have TNS Entires in MYSQL?
    Like Toad do we have any GUI tool?
    Pleas let me know what are all differences and what challenges we face during migration?
    I also want to know what is the workaround?

    We have gathered some materials onit. But i want to know whether anyone really involved this kind of project and what they have faced while migration ?
    Please if u have documented any such issues and what are all workaround done in this project.please post me some documnets to maymail id radhika.kodepaka@gamil.com which will help us.

    I also want to know whether do weh ave sequence concept in MYSQL,if at all we have this concept in my sql, how can we modify the script if the same sequence is used in more thatn one table. please explain with some example
    In advance ,
    Thanks & Regards,
    Radhika
    Last edited by radhika_kodepaka; 04-12-10 at 06:35.

  2. #2
    Join Date
    Sep 2009
    Location
    San Sebastian, Spain
    Posts
    880
    Hi Radhika,

    unfortunately there is no one to one mapping of objects in Oracle to MySQL. You will need to look closely at each table that you migrate across and how it will work in MySQL. For instance, if there is a table using sequences in Oracle, in MySQL there is no equivalent feature other than auto_increment at the table level. This may or may not be sufficient for your case and this will need to be determined on a case by case basis.

    As for TNS settings these are controlled in my.cnf. You should read the documentation about this. If you are using secure connectivity then you will also need to include OpenSSL in your my.cnf configuration.

    I have gone through migrations before and the complexity is dependent on the applications using the database and the types of objects in the database. The more features of Oracle that you are using the more complex the migration process will be. In the end even after migrating you may end up with problems with performance in which case certain sections may need to be rewritten. MySQL has a rich set of features that can match those of Oracle's. You will need to make sure you fully understand both Oracle and MySQL before attempting to start the migration.

    Lastly, on large projects performance always becomes a major point of contention. To avoid this you should get and set expectations early as to how this is going to perform after migration. This then gives you a clearer understanding of what you need to deliver and at what point it is acceptable.
    Ronan Cashell
    Certified Oracle DBA/Certified MySQL Expert (DBA & Cluster DBA)
    http://www.it-iss.com
    Follow me on Twitter

  3. #3
    Join Date
    Sep 2009
    Location
    San Sebastian, Spain
    Posts
    880
    What you are talking about here is the reorganization of tables within a database. As entries are added and removed you can get fragmentation within the database files. Now the nature of your application blog entries suggests that more and more data is added to the database. There are very few updates or deletes taking part. In which case the amount of fragmentation is limited. What I would suggest more than defragmenting the tables is to rebuild the indexes. Over time your indexes may become skewed with entries being added. A rebuild of the index will reduce the amount of space used by the index making it more efficient to access the data and also optimize the index for data access.

    If you want to clean your database, then the suggested method by MySQL is to backup your entire database. Remove the database and restore your backup. The backup is simply CREATE TABLE, INSERT and CREATE INDEX statements.

    Hope this answers your question?
    Ronan Cashell
    Certified Oracle DBA/Certified MySQL Expert (DBA & Cluster DBA)
    http://www.it-iss.com
    Follow me on Twitter

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