> It's probably because I'm a rubbish database engineer, so stick with my strengths.
This doesn't make you a rubbish database engineer. Scaling databases is complex, so it makes sense to have your source of truth database do only the things it must do (consistent updates, indexing the ranking value if needed for queries) and things it's good at, and move everything else (calculating the ranking value) to another part of your system. If you can keep database load low enough to avoid sharding, that's a big win; you don't have to not grow your DB, just grow slower than Intel grows CPU performance / accessible RAM.
This doesn't make you a rubbish database engineer. Scaling databases is complex, so it makes sense to have your source of truth database do only the things it must do (consistent updates, indexing the ranking value if needed for queries) and things it's good at, and move everything else (calculating the ranking value) to another part of your system. If you can keep database load low enough to avoid sharding, that's a big win; you don't have to not grow your DB, just grow slower than Intel grows CPU performance / accessible RAM.