Earlier this spring, we upgraded our database cluster to MySQL 5.6. Along with many other improvements, 5.6 added some exciting new features to the performance schema.
MySQL's performance schema is a set of tables that MySQL maintains to track internal performance metrics. These tables give us a window into what's going on in the database—for example, what queries are running, IO wait statistics, and historical performance data.
One of the tables added to the performance schema in 5.6 is
table_io_waits_summary_by_index. It collects
statistics per index, on how many rows are accessed via the
storage engine handler …