Query optimization

Control post revisions: WP_POST_REVISIONS, filters and cleanup Every time a post is updated, WordPress saves the previous version as a revision: a row in the posts table with post_type = 'revision' and the post as its parent. Revisions are a good safety net, but without a limit they pile up. A site with a few…

The WordPress object cache: wp_cache_set(), groups and persistent backends WordPress has a key-value cache built in. get_post(), get_option(), get_term(), user and meta lookups all store their results in it, so the same data is read from the database only once per request. Your own code can use the same cache with wp_cache_get() and wp_cache_set(). By…

Avoid N+1 queries in WordPress: prime the meta and term caches The N+1 problem: one query fetches a list of N items, and then every item in a loop makes one more query for its related data. With 50 posts that is 51 queries, with 200 posts it is 201. In WordPress it usually happens…