Sounds like "yes, with an if" where the "if" is "if you don't really care about data consistency".

"Last write wins" sounds like a recipe for disaster IMO.

This is still one of those things that keeps people on MySQL - there are not one, but two open-source solutions available that provide synchronous cluster replication, allowing for "safe" writes against multiple primaries.

Out of curiosity, what conflict resolution options exist in mysql and/or mysql cluster (never checked / exp. in PG)? Because you'll always have to address conflicts of course - we come to CAP / PACELC. Hm [1][2] - looks like they support more strategies (possibly) but I mean none of them are somehow magical, and timestamp comparison based methods comprise the better part of offered strategy set (looks like?) - and "latest timestamp wins" at least used to be the default (did not read thoroughly mind you, was just curious)?

But I could be totally wrong - (1) curious if someone could link to things / explain, and (2) fyi ('stephenr) last write wins based on timestamp is a thing im mysql world as well (though again maybe set of options / different conflict resolution methods available is larger in mysql?)

[1]: https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-replic...

[2]: https://dev.mysql.com/blog-archive/enhanced-conflict-resolut... (nice writeup, maybe outdated idk?)

For reference those two pages are both about NDB cluster.

The two "options" I was referring to are MySQL group replication and the Galera replication plugin for MySQL. Both provide synchronous replication, so the write either succeeds to a majority of the cluster or is rejected.

Understood, thanks! I wasn't even sure where to look - thank you

It's all tradeoffs, with MySQL multi-master and multi-source models having their own issues and pg also has other options with their own tradoffs.

ACID+distributed== tradoffs that will always keep this a horses for courses problem.

Just for my own understanding, could you clarify why you think "last write wins" is a recipe for disaster?

Because two simultaneous writes mean some change is just lost, without feedback to the writer.

Did Postgres ever get a built-in, blessed replication offering? It's been a while since I set it up, but I remember this was always a big missing feature compared to Mysql.

The basic replication mechanisms have been built-in for quite a while. What’s not there is cluster management (replica launching, leader election, load balancing, that sort of thing) that makes it practical in a nontrivial situation. There are several 3rd party solutions to that. [0]

Same situation as, e.g., backups. You can just use pg_dump, but to be serious you need a 3rd party solution that does log shipping and so on.

[0] https://www.postgresql.org/download/products/3-clusteringrep...

Streaming and logical replication is built in: https://www.postgresql.org/docs/current/runtime-config-repli...