- first, as you said, mysql is included in all linux distribution.
Postgres is becoming more common. All my new servers came with it installed. If you're able, PG is really pretty easy to install on linux.
- In php the function are built-in.
Yep. I think there was talk on php-internals about making mysql not enabled by default, and actually making PG functions enabled by default. I don't think it had enough support though. But they're going to have sqllite by default (which I don't think I'll ever use).
- It's free. (for now... ).
So is PG. MySQL is trying some funky stuff with their licenses. There was a page on their site that said, basically, if you develop an application that is intended to use MySQL specifically, then you, as a developer, need to buy licenses.
- It's very apache friendly.
- don't require a lot of HW.
All true with Postgres. I just got some new redhat 9 servers - PHP+Apache2+PostgreSQL is definitely performing better than my old RH7-PHP-Apache1-MySQL servers. I also have had problems with MySQL on these servers - on one mysql ate up all the memory, or the other it ate up all the cpu. No idea what the problem was.