During my ETL development work, there have been instances when I had to do a DDL change in the Data Mart tables, sometimes for an enhancement or because of bug fixes.This involves fixing the Kettle Transformation as well. For this you need to follow this simple yet useful practice.
•Clear Database Cache whenever you do a DDL operation on Lookup or Target tables otherwise Spoon might mark Transformation as Invalid on Validation.
Whenever we introduce a table in Kettle, it keeps a cached version of the table metadata into the repository so as to optimize the transformation viewing/editing. But it doesn’t refresh this metadata from database every time we open the transformations as its memory expensive operation. For this reason we have to manually clear this cache whenever we make a change to the Database tables.
•For this you need to click on the Target (or Dimension Lookup) Step and then Click on SQL and then hit Clear Cache. It’ll ask you to Clean Cache only for this Table on Entire Database.
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