Data Replication

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It is possible to apply CDC in record level.

  • 1.  It is possible to apply CDC in record level.

    Posted Thu July 01, 2021 02:36 PM
    We are using IBM Infosphere information server 11.7.0
    We are performing ETL from DB2 to SQL Server and want to use CDC to track record level changes while loading from source to target. Is it possible to obtain an exact system timestamp for a specific record when it is loaded from the legacy source to the target?
     Thank you in advance for your Expert advice.

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    Andrew GK
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  • 2.  RE: It is possible to apply CDC in record level.

    Posted Thu July 01, 2021 02:51 PM
    Hello

    Yes it is possible to get a timestamp from the source transaction of when the change was made and incorporate this into the target data.

    The precision of the timestamp is governed by what the source database itself offers. DB2 is a good example, because the timestamp from DB2 LUW only goes down to whole seconds, while for DB2i and DB2 on zSeries you can have a precision in milliseconds or even better.

    However if you wish to use the timestamp for sequencing even with a greater level of precision than seconds, you will still have problems, as you could have multiple updates for the same row in the same unit of work (business tranasction) with the same timestamp. It is therefore necessary to use a different method such as a sequence or identity column on the  target to establish the correct sequence. Note that generally if there is a single subscription (replication stream) between the source and the target then CDC can guarantee to apply the changes in the same sequence on the target as that in which the changes were committed on the source.

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    Robert Philo
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