[bgrainger]

Some MySQL clients offer this; for example MySqlConnector has a `ConnectionIdleTimeout` setting that controls how long a connection can be alive in the pool: https://mysqlconnector.net/connection-options/

This is generally useful to "prune" the number of open connections in the connection pool after a burst of activity has happened, so I'm surprised more clients don't offer it; I couldn't find an equivalent setting on go-sql-driver/mysql or MySQL Connector/J.