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  1. #1
    Join Date
    Feb 2008

    Unanswered: Replication Issue with CLOB columns

    I am working on DB2 Version 8.1 Fixpack 10. My O/S is AIX.

    I have a SQL replication setup in my database(production).I have a table with CLOB colums. All the column data is replicating good from the source to target except CLOB columns till this date.

    With the same dprop settings on test and development databases working good including CLOB colums.

    So, here my question is,why this CLOB column data is not replicting in the production databases.Is there any updates needed in the ASN tables.

    Please help me in this:

    Thanks in Advance

  2. #2
    Join Date
    Mar 2006
    This is my guess. Replication use the journal entries. DDL for creating a CLOB column has option to say wether it is logged or not. Probably in your case the CLOB is not marked logged and that could be the reason why it is not replicated.



  3. #3
    Join Date
    Jan 2007
    Jena, Germany
    Another restriction on LOB columns is that the CD tables only contain an "update indicator", i.e. a flag saying whether the LOB was changed ('U') or not (NULL). The Apply process will, upon discovering the 'U', issue a query against the actual source table to grab the real LOB value and send it to the target database. The obvious issue with that is that CD table entries are not synchronized with the source table, i.e. Apply may read a newer LOB value. Depending on your scenario, this may result in seeing no visible change - for example, if you change LOB value A to B and then back again. The advantage of this approach is that the LOB values will not be copied to CD tables, doubling the amount of space required.
    Knut Stolze
    IBM DB2 Analytics Accelerator
    IBM Germany Research & Development

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