What is the WordPress query cache warm-up strategy and how does persistent object caching change the behavior of `update_post_meta()`?

Question

WordPress Expert — Hard

What is the WordPress query cache warm-up strategy and how does persistent object caching change the behavior of `update_post_meta()`?

Accepted Answer

With persistent object caching, update_post_meta() updates the database, then calls wp_cache_delete() on the post's meta cache group, ensuring the next read repopulates from the database. This read-through pattern is crucial in preventing cold-cache database storms.