At the top of each page there is a Search all the things field. Type in what you are looking for and it will search across customers, tickets, products, and more—just about everything on your site.
Sometimes when a big feature improvement comes we need to rebuild our search database. We have a nice fallback system in place, but it's not quite as powerful as the "real thing".
What normally works
Normally our search is powered by a super powerful search engine to allow you to Search All The Things. Note that it does not search ticket comments or custom fields.
What works during the maintenance window
When we are performing DB maintenance on the search engine we fall back to a simpler database query, so basically, the individual pages, Customers, Tickets, Inventory, etc. have basic search capabilities.