A variable product with four sizes and three colours is not one row. Every combination is a product_variation post carrying its own meta, so a catalogue that reads…
The activity stream is not posts. It has its own table, its own class and its own template loop, so every habit built around WP_Query — pre_get_posts, fields…
BuddyPress extended profile fields look like user meta and are not. They live in their own tables — bp_xprofile_fields for the definitions, bp_xprofile_data for one row per field…
WooCommerce 2.0 moved order line items out of a serialised _order_items post meta value and into two dedicated tables. Anything that read that key directly — a sales…
Before adding a caching plugin to hold one expensive query, WordPress already has the API: set_transient() and get_transient(), with a time to live and no configuration. It uses…