I run Postgres since about 2016. I used to run MySQL behind the same frontend app.
I barely know anything about Postgres beyond installation for our use case, backup and recover. I used to know loads about obscure MySQL optimization techniques, fixing broken tables, fiddling with scary parameters and recovering from hair raising situations.
One example of the sort of trivia that's burned into my brain: You never want to use the utf8 encoding. It's broken. What everyone else calls utf8 MySQL calls "utf8mb4". MySQL is filled to the brim with this sort of thing.
Isn't that just more about the abundance of hardware we have these days? While on the MySQL side you had to delve into tweaking the different cache sizes and picking MyISAM or InnoDB depending on the use case, on Postgres you had to deal with stuff like manually running VACUUM at the right time or later when that arrived tweaking the autovacuum params.
These days even on my "underpowered" NAS I can just run a default docker image of my database and not worry about tweaking anything.
I barely know anything about Postgres beyond installation for our use case, backup and recover. I used to know loads about obscure MySQL optimization techniques, fixing broken tables, fiddling with scary parameters and recovering from hair raising situations.
I like my current state of ignorance.