[vlovich123]

If I apply your reasoning, is there anything that is a footgun? I can just excuse anything as you are just expecting the universe to magically fix all of your mistakes & then the word loses all meaning.

Footguns are when your expectations are subverted in surprising ways. It means the system is set up to point a gun on a hair trigger at your feet and then just wait for someone to bump in and set it off - you could blame the person who bumped into the footgun or you could consider that maybe you shouldn't be pointing a gun at peoples feet on a hair trigger & blaming the person who was unlucky or clumsy enough to bump into it. Subverting reasonable expectations, having defaults tuned for the minority situation, and having inconsistent defaults are all footguns in my opinion. Footguns can be unavoidable in many cases when you don't have any reason to believe there is a majority or minority usage pattern, but that doesn't seem to be the case here based on what the author & people in the thread seem to be saying.

Arguing that someone needs to learn arbitrarily many things to properly use a tool is just gatekeeping; this isn't the only footgun in Postgres. If you notice, there's reflection going on here on whether there may be ways to improve the tool to begin with (e.g. maybe the default for FKs should be to index them given that that's what people usually do on FKs anyway & it's the default for PKs).

[redeeman]

I think footguns are something thats 100% unexpected. I would argue that a user of a database that sees any kind of reasonable size ought to be very aware of how things work, because to be blunt (to use same language as GP), if you are caught off by this, chances are that you are not qualified to tackle the thing you're doing. It is scary how many in high positions have no clue about indexes, and either are unaware, or have gross misconceptions about how things work