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Working with unsupported datatypes like XMLTYPE during Migration

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We have a customer with a migration coming up where we'd like to use Dbvisit Replicate. The main issue is that all the tables they have include xmltype columns. We are considering converting them to Varchars or Clobs for the migration. Just wondering if you've had customers do this in the past, and what lessons or gotcha's were learned?

Answer

Because Replicate does not support XMLTYPE data type, for the most part we just have customers exclude these columns from replication with our application.

Of course, with a migration it is highly likely that you do want this information pushed to the new location, so we have also suggested to customers that they should exclude those tables with these columns from the migration, and then exp/imp (or datapump) those tables separately before the cutover.

A question to consider is will the application use the data at all during this migration?

  • If it does not care that it's not an XMLType anymore, if they won't be modified during the migration, you can just ignore them, Datapump or whatever to target, then exclude.
  • If they will be modified/add-new during that time, then using Varchar2/Clobs is a good way:
    • Varchar2 is much simpler and safer, and is what we would recommend. It may also be faster for export/import.
    • CLOBs can be used in unsupported and innovative ways (like compression, encryption, deduplication).
Mike Donovan Answered

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