We regularly receive support cases in which the root cause is a database connection closure. Whenever we receive such a case, we refer the customer to the Surviving Connection Closures documentation, and ask them to add the validation query.

As this type of problem could have consequences to the data integrity of Jira, I was wondering if we should recommend that setting in the standard database configuration, like in: http://www.atlassian.com/software/jira/docs/latest/databases/mysql.html

Of course, running the validation query may have a performance impact, specially for environments where the is a high network latency. It would be good to know how regularly this query is run (once every time we request a connection from the pool? once before every SQL command?) and how it impacts Jira. Maybe with that information we could make a decision on whether all customers should set that type of validation.