There's a quiet kind of frustration that comes with looking at 90,000 rows of data and realizing the fix you need is buried somewhere in your memory. That's exactly where this user found themselves: they'd done the anonymization before, but the how had slipped away. And the real pain point wasn't the scale of the task, it was the fear that doing it right would require building a lookup table for thousands of unique usernames. That fear is understandable, but it's also unnecessary.
What this person is describing is a problem with a surprisingly elegant solution, one that doesn't demand a master list or hours of manual mapping. The core insight is that you don't need to know every username to anonymize them all. You only need a pattern that consistently replaces the variable part while preserving the structure. The old trick they remembered, turning "@username" into "@xxxxxxxe", works because it doesn't care what the original name was. It just needs to recognize where the mention starts and where it ends, then swap in a placeholder that keeps the text readable but no longer identifiable.
For anyone staring down a similar wall of data, the practical takeaway is this: Excel has functions like SUBSTITUTE and REGEXREPLACE (in newer versions) that can handle this without a lookup table. You're not chained to the idea that every unique value must be cataloged before you can proceed. The user's instinct to avoid building a manual reference was correct, that would have been the slow, brittle path. The better path is to write a formula that applies the same transformation to every row, letting the pattern do the heavy lifting. It's the difference between sorting through a haystack by hand and using a magnet.
The fact that this person can't recall the exact steps they used before isn't a failure of memory; it's a sign that the solution was simple enough to be forgettable. That's worth holding onto. When a process feels like it should be easy, it often is, you just need to rediscover the right approach. So if you're sitting on a similar dataset, don't let the scale intimidate you. Start with one formula, test it on a few rows, and let the pattern do the rest. The answer isn't in a lookup table; it's in the structure of the problem itself.