issues, PRs, comments share more than one dependent tables:
- reactions
- mentions
and I found that issues/PRs/comments all have a field body
So it seems doable to have unified bodies or rich_texts table to replace the body field from all three(or four) tables (issues, pulls, comments, pull_comments).
Now we can save/retrieve reactions/mentions in more proper way.
I don't think we need this. Referencing between records is already pretty dynamic due to the nature of AT-URI. We don't need to (or shouldn't) constraint links between records.