Thanks for sharing this, it's been fun to play with. I've been poking around a bit, looks like `skip locked` was added back in v9.5.
For those who are interested in how it works, here are a few links that might be useful:
- [What is SKIP LOCKED for in PostgreSQL 9.5?][2ndquadrant]
- [Postgres 9.5 feature highlight - SKIP LOCKED for row-level locking][otacoo]
- [The Skip Locked feature in Postgres 9.5][pgcasts]
The 2ndquadrant post points out that Oracle and SQL Server have similar functionality. Mysql didn't at the time, but [seems to have added it in 8.0.1][mysql]
[2ndquadrant]: https://www.2ndquadrant.com/en/blog/what-is-select-skip-lock...
[mysql]: https://mysqlserverteam.com/mysql-8-0-1-using-skip-locked-an...
[otacoo]: https://web.archive.org/web/20160626090321/http://michael.ot...
[pgcasts]: https://www.pgcasts.com/episodes/the-skip-locked-feature-in-...