Review of MySQL 5.6 Defaults Changes

James Day just posted the great summary of defaults changes in MySQL 5.6 compared to MySQL 5.5

In general there are a lot of good changes and many defaults are now computed instead of hardcoded. Though some of changes are rather puzzling for me. Lets go over them:

back_log = 50 + ( max_connections / 5 ) capped at 900 – The large backlog is needed when there is a high rate (spikes) of connections which is rather unrelated to number of connections. You can get 1000s of connections a second even from as little as 100 connections, hence max_connections would be small. I think this is the case where somewhat higher fixed default (even 900) would be better than trying to be overly smart.