I ran through roughly our numbers here [1], it looks like self-hosted costs us about 25% of AWS.
I didn't include labour costs, but the self-hosted tasks (set up of hardware, OS, DB, backup, monitoring, replacing a failed component which would be really unusual) are small compared to the labour costs of the DB generally (optimizing indices, moving data around for testing etc, restoring from a backup).
I ran through roughly our numbers here [1], it looks like self-hosted costs us about 25% of AWS.
I didn't include labour costs, but the self-hosted tasks (set up of hardware, OS, DB, backup, monitoring, replacing a failed component which would be really unusual) are small compared to the labour costs of the DB generally (optimizing indices, moving data around for testing etc, restoring from a backup).
[1] https://news.ycombinator.com/item?id=46910521