Besides posts and pages, every WordPress database has a table called wp_options . It stores site-wide settings: the site title, the permalink structure, the list of active plugins, and the configuration of each plugin, one row per setting.

That table has a column named autoload . It looks like a simple flag, but any row with autoload enabled is loaded on every single request , whether that request needs it or not. When a long-running site's admin screens gradually get heavier, a bloated autoload set is one of the first things worth checking.

Following the previous article on database index basics , this post uses measurements taken on this blog's own WordPress database (7.1 series), using read-only queries only, to explain how autoload works and what happens when it grows too large.

wp_options: the home of site-wide settings

wp_options is a simple key-value table: option_name , option_value , and an autoload column. On this blog it holds 215 rows.…