Doctor Jones and I both keep the MySQL Performance Blog in our respective feed readers because you regularly get amazing gems like today’s post about the possible optimization for sort_merge and UNION ORDER BY LIMIT. This is an approach to writing a query that I would not have thought would be more efficient than a simple WHERE clause with OR, but my tests on even a moderately filled database like ours shows a noticeable difference. Heck, even the MySQL manual mentions this approach for searching on two different keys. You learn something new every day. For ExpressionEngine and CodeIgniter developers out there, I highly suggest subscribing to their feed today.
