What Are the Biggest Challenges You've Faced With Your ETL Pipeline? or How Do You Optimize Performan

"Just restart it" is *not* the answer, lol.

I swear by unit tests for each transformation step. If something fails, I know *exactly* which function to blame.

Also, logging the input/output of each step? Game-changer. No more "how did this value get here??" moments.

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