Hi - I deleted a column from a Snowflake table. Th...
# gooddata-platformm
Mitchel Roling
08/10/2023, 7:45 PMHi - I deleted a column from a Snowflake table. The column wasn't referenced in the data model, but other columns in the table are. I'm now getting an error saying the column is missing, but I'm confused why it is happening. It's almost as if the column is cached somewhere. Is there any way to safely remove unreferenced columns from source tables?
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Michael Ullock
08/10/2023, 8:24 PMHi Mitchel, when you’re going to change your LDM and delete some attributes in datasets you can check the impact like so:
• In GoodData Platform, there is an indicator of impact in the summary of your changes. Click on “Dependencies detected” as displayed on the image.
• GoodData Cloud released a similar feature in October, called Impact Analysis. https://www.gooddata.com/developers/cloud-native/doc/2.4/model-data/evolve-your-model/monitor-model-changes/
Please note that both UI’s search for impact only in the given workspace.
So before removing columns from source tables, you should always check the impact.
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Mitchel Roling
08/10/2023, 8:25 PMHi @Michael Ullock - I removed the table from Snowflake only. It was never referenced in GoodData and as far as I can tell, exists nowhere in my LDM.
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Michael Ullock
08/10/2023, 8:28 PMCan you please tell me which GoodData product you’re using? Is this related to the GoodData Platform or GoodData Cloud?
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Mitchel Roling
08/10/2023, 8:28 PMI believe I'm on Platform
Mitchel Roling
08/10/2023, 8:30 PMMitchel Roling
08/10/2023, 8:31 PM@Michael Ullock - Here are the logs. CURRENT_FOLLOWER_COUNT (INTEGER) was in the table, but it wasn't referenced anywhere. I added a placeholder field back so that it would refresh again, but I don't know why the field is necessary to refresh.
Mitchel Roling
08/10/2023, 8:32 PMAnother view of my model... no reference to the field anywhere.
Mitchel Roling
08/10/2023, 8:57 PMOk @Michael Ullock - I tried adding the field into the model, and now I'm getting a new error: LDM field fact.linkedin_daily_follower_statistics.current_follower_count is not mapped to any source column
It's definitely mapped. And when I tried to delete the field again, the error now persists and the data won't refresh.
Mitchel Roling
08/10/2023, 9:02 PMThe only reference to the field that I can find is in the Manage > Model section where the field is listed as a deleted attribute
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Michael Ullock
08/10/2023, 9:11 PMSorry for the delay in getting back to you - From the last screenshot you have attached, I can see that the Attribute has not been deleted, but rather “Disabled” - This means that the attribute was only deleted from user interface only. The way how to remove attributes and facts from the project is to use MAQL DDL, using DROP attribute function, which you can find described here:
https://help.gooddata.com/doc/enterprise/en/data-integration/data-modeling-in-gooddata/data-modeling-and-maql/maql-ddl/
Michael Ullock
08/10/2023, 9:13 PMRegarding the new error:
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LDM field fact.linkedin_daily_follower_statistics.current_follower_count is not mapped to any source columnm
Mitchel Roling
08/10/2023, 9:14 PMYeah, I removed the filed in the UI, but the error persists.
Mitchel Roling
08/10/2023, 9:14 PMLooking into the drop API call now
Mitchel Roling
08/10/2023, 9:21 PM@Michael Ullock - Ok now I get this error: Can't delete object (%s) while referenced by dependent objects (%s). Use 'CASCADE' to force a drop of all references to this object. A 'CASCADE' drop will make the following changes: DROP %s, MODIFY %s.
Mitchel Roling
08/10/2023, 9:22 PMI tried DROP CASCADE and CASCADE DROP but got a syntax error for both. What's the best way to structure the query to drop this field
Mitchel Roling
08/10/2023, 9:27 PMSorry, need to run to pick up the kids. What if I just delete the entire table from the model and add it back? Would that work or would I end up with all the fields stuck hidden on the back-end?
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Michael Ullock
08/10/2023, 9:31 PMYou call should look something like this:
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DROP {attr.example} CASCADE;
SYNCHRONIZE {dataset.example} PRESERVE DATA;PRESERVE DATAPRESERVE DATASYNCHRONIZESYNCHRONIZEPRESERVE DATAm
Mitchel Roling
08/10/2023, 9:55 PMGot it, I was putting the word CASCADE before the attribute, not after. Ok, I was able to get it to work. Thanks so much for your help and patience.
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Michael Ullock
08/10/2023, 9:58 PMYou’re welcome Mitchel & thanks for getting back to me and letting me know you’re all set. Hope you have a great rest of the day ahead 🙂