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As your question is fairly general, this answer is too. I'd insert the ETL process itself into the target database. As you have on-site developers this will have to be included in your extraction ...
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Source: https://writers.stackexchange.com/a/33480 License name: CC BY-SA 3.0 License URL: https://creativecommons.org/licenses/by-sa/3.0/
#2: Initial revision
As your question is fairly general, this answer is too. I'd insert the ETL process itself into the target database. As you have on-site developers this will have to be included in your extraction development. Best add a bit of architecture description and versioning as well to serve the level of understanding of your consumers. When going after this I'd include a similar step in the actual extraction run process; even a straightforward run-date and field for comments can be worth gold when attempting to generate trends a year hence.