> * Missing database indexes. A lot has been written about this, and it can cause a slowdown of N or N^2 times in some cases. Adding an index in the right place

> * Missing database indexes. A lot has been written about this, and it can cause a slowdown of N or N^2 times in some cases. Adding an index in the right place can change a linear scan into a much faster B-tree search. I can give a personal piece of anecdata on this. I was using a static application security testing tool on a huge repo (over 2M lines of code). It reported a couple thousand issues, nearly all of which were issues on code style rather than actual security issues. Generating a report would take literally 2 DAYS and would grind the database server so hard that any other use of the SAST suite had a noticeable impact. I decided to run a profiler and see what queries were hitting it so hard. Turns out there was a SELECT that was being used a lot, but the columns being searched weren't indexed. I don't remember the exact query, but I'm guessing it was searching all the code in the repo that was stored in the database repeatedly. I manually ran a CREATE INDEX. It took about a day for it to complete, and it added a couple gigabytes to the database. But now, those reports went from 2 days to about 20 minutes. > If you’re writing Java code that has to make calls ten levels deep to get anything done, those levels of indirection aren’t free. I'm of the opinion that any time you're performing type introspection, reflection, and ".invoke()", it's a code smell, but I suppose middleware in Java is impossible without them due to its draconian type system.