300,000 lines of Python… The company had bought Ellington, a Django based CMS, but the team basically rewrote the entire thing using multi table inheritance (u

300,000 lines of Python… The company had bought Ellington, a Django based CMS, but the team basically rewrote the entire thing using multi table inheritance (unintentionally), so everything in the database had two copies, and we had over 70 tables, hundreds of gigabytes, disasters every week and tons of bugs... I discovered this more than a year later and nobody was even aware. Even the DBA wasn’t aware the tables were duplicates.