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  1. #1
    Join Date
    Dec 2003
    Posts
    148

    Question Unanswered: Migration & Data Type Conversion Question

    Hey All.
    I'm in the process of a SQL Server 2k to Oracle 9i migration. Since the Oracle Migration Workbench refuses to work (long story) I'm going to have to use some other method(s). That issue aside, I noticed if I use DTS it frequently (always?) converts the SQL Server VARCHAR datatypes to CLOB datatypes. I don't have much Oracle experience but I believe these are used for ASCII characters up to 4 GB. Will this effect the performance of the Oracle DB (NOTHING is going to have more than say 355 chars of info, I clearly do not need a CLOB datatype) What are your experiences with migrations and more specifically data type conversions and how you avoided and/or dealt with them?

    Also - It seems strange that if I DTS a table and its' data, and then I "Create like" to just keep the field names and datatypes - I cannot change the datatype of a field even though it is empty. So basically, even though there is no data in the table, I cannot change the field datatype from CLOB to say, VARCHAR2. Is there a reasonable workaround for this? Any advice pertaining to SQL to Oracle Migrations on any level will be appreciated as I've never really taken a project like this on.
    Thank You to Everyone in Advance.

  2. #2
    Join Date
    Nov 2002
    Location
    Desk, slightly south of keyboard
    Posts
    697
    Hi,

    I'm afraid I havent done any SQL Server to Oracle migration, but your thoughts are correct... LOBS (CLOBS, BLOBS etc) do have a performance impact and you should avoid them unless you have a reason to do otherwise.

    Sorry I can't be more helpful :-)

    Cheers
    Bill
    Please don't email me directly with questions. I've probably just got home from the pub and cannot guarantee the sanity of my answers. In fact, I can't believe I actually made it home.

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