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Whatever migration issues a model may experience, experience suggests that most Cognos Enterprise Planning Migration sites will run into trouble over ‘Sorcerors Apprentice Links’. In Cognos EP, Links are really easy to create through a quick point and click. That in itself is the problem – they are really easy to create – so many of them! Unfortunately they are also rather difficult to delete! This is not only because the software hangs on to them (a Link referenced in a Macro cannot be deleted), they also strike fear into the hearts of anyone who has not written them!

Story of the Simple 2 Link Cube & the 10 Link Monster

Consider the example of a Simple ‘2 Link Cube’ that grew into a ‘10 Link Monster’:

sorceror image1

The 1st Cognos Administrator set up a simple 2 Link Cube. Then along came the 2nd Cognos Administrator who added Links 03,04,05,06 for reasons now forgotten & undocumented.

When the 3rd Cognos Administrator arrived, who didn’t want to break anything so just added Links 07,08,09,10 on top. Link 07 overrides Link 01 – Link 09 overrides Link 02 – Link 10 overrides Link 07 – Link 08 was for something else to keep, just in case!

Then along came the 4th Administrator whose job was to Migrate to TM1, and tried to use the TM1 Migration Utility but the Links generated so much useless Script that the Links were binned. After trying from scratch again, the specification was too high-level and so ended up repeating all the errors of the previous Administrators’ work.

Well this couldn’t happen in real life – or could it?

Do I have ‘Sorcerers Apprentice Links’?

In a word “Yes” – everybody does. Hence, why ‘Sorcerors Apprentice Links’ is the second of ‘Top Ten Tips for Cognos EP Migration’.

In 25 years of trouble-shooting Cognos EP solutions, I never once came across a site that did not have high maintenance or redundant Dlinks. The only question was “How many?

If you are not sure whether you have Sorcerors Apprentice Links the most obvious pointer is your Dcube Update Table. If there are more links feeding into the Cube than items in the Update Table then you may well have an issue. If Standard & ODBC Links are mixed together in your Update Table then you probably have an issue. If your Link names are not Tgt Cube < Src Cube (Optional Simple Note) where Tgt Cube & Src Cube are standardized short Cube names then you definitely have an issue.

I have ‘Sorcerers Apprentice Links’ – What now?

Your Triangle EP Health Check will tell you your best course of action. But if you want to go it alone I recommend you immediately tidy up your Link names. You then need to work out a Standard Policy to define which Links should be in the Dcube Update Table vs which Links should be actioned directly by a Macro. Your Link naming convention should then help you drive out cobwebs from your model:

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  • Standard Links named “STD Tgt Cube 01 < Src Cube” actioned by DcubeUpdate Macro
  • Standard Links index “01” refers to the Order of the Link in the Dcube Update Table
  • ODBC Links named “OBD Tgt Cube 01 < Src Cube” actioned by DlinkExecute Macro
  • ODBC Links index “01” refers to the Order of the Link in the Macro.

Migration Journey

There are many other tasks you can do to prepare for Cognos Enterprise Planning for Migration but renaming Links is one of the first key steps because there is no possibility of data loss, broken reports or problems with Excel. After this exercise, all links that are not in Update Tables or accessed directly by Macros can be safely deleted and you will be well on the way towards getting your model ready for Migration.

December 17, 2015