I posted this elsewhere in the thread, but I ran some benchmarks on schema changes between the two on 5 million row tables (when deciding to switch) and Postgre

I posted this elsewhere in the thread, but I ran some benchmarks on schema changes between the two on 5 million row tables (when deciding to switch) and PostgreSQL completely clobbered MySQL performance wise: https://gist.github.com/1620133 https://gist.github.com/1620133. As we recently switched to PostgreSQL, one gotcha is that PostgreSQL uses separate process instead of threads for each connection and so it's slower and more memory intensive to establish new connections so connection pools held application side (such as pg_bouncer) are incredibly important.