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Former Member

DB size increases after migration from Oracle

Hello All,

We are performing a heteregenous system copy of an R3 4.7 system from Oracle 10g to SQL Server 2005. However during this export import we are noticing that the DB size is increasing contineously. Whereas my source DB was 5.7 TB used in Oracle my target DB has already climbed up to 6.6 TB. The Import is still on going. Also we are noticing some tables like ACCTIT are almost double in size in target when compared to the source..

Is this is a normal behaviour for MS SQL. Has anyone come across such a case before. If so , can you kindly share some links or documentations highlighting such an event and its cause.

Thanking all in advance,

Regards

Surajit

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4 Answers

  • Feb 24, 2014 at 01:40 AM

    Hi Surajit,

      Do you use unicode? What character sets do you use? SQL server use UCS-2 so in some case it uses more disk space.

    http://docs.oracle.com/cd/B19306_01/server.102/b14225/ch6unicode.htm

    I high recommend you try to migrate to SQL server 2008 with page compression directly.

    PS: maybe ECC6 is required.

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  • Feb 24, 2014 at 05:12 AM

    Hi Das

    1. Could you paste the transaction ST04 screen shot ?

    2. Presently what is the version of SAP R3 system? is this any planning to upgrade?

    Regards

    Sriram

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    Former Member
    Feb 24, 2014 at 06:15 AM

    Hello Dennis, Sriram,

    Thank you for taking an interest.

    Unfortunately I cant give a ST04 screenshot as my import is not yet over.

    My SAP code page is non unicode and it is getting migrated as non unicode. The R3 version is 4.7 Ext 110.

    We are planning to upgrade after the migration is done.

    SQL Server 2008 possibly is not supported for R3 4.7 version.

    Any aspect from the DB which anybody can highlight which maybe causing this situation?

    Regards

    Surajit

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    • Hi Surajit,

      Please check the following

      1) Whether OLTP or OLAP compress was activated on your Oracle database

      2) Check in MSSQL whether Page dictionary compression has been activate. Details on page dictionary compression is as below.

       One-time change with no repetition: Once a table is built with Page Dictionary compression, there is no need to rebuild it in order to apply compression to new content. As data is inserted, it is compressed in the pages automatically, without help from the database administration side.

       Database volume often reduced by half with migrations from competitive platforms.


      Hope this helps.


      Regards,

      Deepak Kori

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    Former Member
    Feb 25, 2014 at 12:07 PM

    Hi Surajit,

    I haven't experienced this before. In most of my migrations the DB has been significantly smaller but it of course depends on lots of factors on the source and the target database. And: on the target side I am usually using SQL Server Release >= 2008 as the more recent releases provide very useful features.

    As I understand the import is still running. With SQL Server database objects can be compressed while there are two different types of compression, row compression and page compression. But these compression types are only available as of SQL Server Release >= 2008 - for this reason it can be possible that if the source DB was compressed on DB level (Oracle provides compression features as well) it will consume more space in the target system.

    Is there a reason why you are not using SQL 2008 in the target system?

    And: where did you check the DB size? Are you really looking at the currently used space? Or are you looking at the allocated size?

    Regards,

    Beate

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