Benjie's responses megathread

I often post useful answers in various locations (chat, issues, PRs, StackOverflow, etc). It'd be great if these answers were rewritten and inserted into the documentation for easy reference. Some might make sense in an FAQ format, some might make sense on the relevant pages of the documentation.

This thread collects some of these responses with the intention of later going through them and putting them into the docs - of course if someone wants to take on doing this that would be very welcome!

One response per message, please; each entry should:

- have a checkbox `- [ ] Added to docs` to indicate completion
- have a source URL or description (e.g. `Discord, #help-and-support, 20th December 2019 @ 3:17pm UTC` (please include timezone!))
- have a copy of the original text _unless_ it was posted on graphile GitHub in which case a link to the comment sufficies

Thanks!