One of our customers asked me whether it’s safe to enable the so-called USER_STATISTICS features of Percona Server in a heavy-use production server with many tens of thousands of tables.
If you’re not familiar with this feature, it creates some new INFORMATION_SCHEMA tables that add counters for activity on users, hosts, tables, indexes, and more. This is very helpful information. It lets you run queries to see which tables get the most reads and writes, for example. Another popular use for it is to find unused indexes.
I knew that some of our customers were using the feature enabled in production all the time, and I knew that Google and Facebook and others (the original developers) did also. But I didn’t know the …[Read more]