Slow dashboard tiles? Check your filters!
Have you ever opened a Looker dashboard with ten filters, watched the tiles spin for longer your expected, and wondered why it’s taking so long when the underlying database is usually fast?
The culprit is often a silent connection storm with the tiles AND the dashboard filters. By default, Looker issues separate, concurrent database queries for every type: string filter on a dashboard the moment it loads, just to populate the suggestion dropdowns. It is the database equivalent of a restaurant kitchen prepping every single menu item the second a customer sits down, before they have even opened the menu.
Before trying to optimize these queries, ask yourself: do your users actually need dynamic suggestions for all of these filters? If a field has high cardinality (like a user_uuid) or if the values are static and change only once a year, you should not query the database for suggestions.
Let's look at why this happens and how to manage suggestions in LookML to protect your database connection pool.