[MarkusWinand]

I wonder why you are so focused on SQL:2011? Since then there was SQL:2016 and now there is SQL:2023.

Also, which features in particular are you missing in PostgreSQL? Merge was added with PostgreSQL 15 a year ago: https://modern-sql.com/caniuse/merge

[rjbwork]

2016/2023 got pretty widespread support across databases for the functionality I care about, both before and after adoption - namely the JSON stuff. MSSQL also already had pretty good graph support AFAIK, although I haven't used it that much.

I find the temporal table stuff really useful and they drastically simplify a number of requirements, so it's annoying that the only non-proprietary DB that supports it is maria.

[refset]

Temporal tables, most likely. Although even SQL Server only supports system time versioning, not full bitemporal tables (as per the spec).

[MarkusWinand]

The existing implementations (Oracle DB, SQL Server, MariaDB, Big Query) come with their problems too. I was a big fan of the new features when it came out in 2011, but pratically there is an unsolved elephant in the room: It doesn't cover schema changes.