At work, we’ve always used and advocated MySQL for high availability mission critical applications thanks to it’s built in binary replication features.
This was a feature PostgreSQL sorely lacked but it is some thing that has also been rectified in the 9.0 release which, among many other features, includes:
- Hot standby;
- Streaming replication; and
- In-place upgrades.
We’ll be studying and testing this new release carefully as, despite the previous lack of the above features, PostgreSQL had a lot of other features over MySQL and was also ahead of MySQL with such taken for granted features as views, triggers and stored procedures.