MySQL – How to Put Database into Maintenance Mode

Your second solution using the LEFT JOIN is by far the best approach. I would not use a temporary table, I'd use a regular table and populate it with new values any time you wanted run the query.

First things first. Make sure you have developed and documented a disaster recovery (DR) strategy. Spend some time thinking up ways that things can go wrong, how to recover from them, and testing them to get an idea of how long it will take, especially when restoring from a backup. Some general ideas:

• mysql crashed, but server is fine: fix error and start mysql.
• MySQL has to be restored from a backup: restore from a backup and start mysql <-- test this before it becomes something you have to do in an emergency.
• Server died and has to be replaced: get a replacement server in place and restore from a backup.

Once you have a DR strategy and a method developed to test your backups in place, then you can move in to more periodic tasks:

• test your restore process regularly. This ensures familiarity in case when it's necessary.
• ensure proper indexes. If you're using percona server, you can get statistics on which indexes are unused after a given time (month or so)
• slow query review. Enable the slow query log with long query time of 1second or so and use pt-query-digest to review them on a weekly/monthly basis.
• read http://www.mysqlperformanceblog.com/ and blogs from http://planet.mysql.com/ .. on such a tiny database, you'll rarely have many of the performance issues of interest. So you'll have plenty of time to read up on interesting issues and how to resolve them.