A big project in my company. Had some annoying race condition that caused data to get deleted when two processes finished in the wrong order they hit the dB and override each other’s work.

Long story short. Fixed the bug and in the process the codebase shrunk by 60%. I didn’t have to delete the rest of the code, but the bug was due to a function in the legacy section of the code, and found out that it was the only function used in that section.

So I deleted it. Rewrote the function so it upserts. And bam. Smaller, cleaner code :)