Ticket #5718: add_post_meta-cache-corruption.diff

wp-includes/post.php

@@ -485 +485 @@
         if ( $unique && $wpdb->get_var( $wpdb->prepare( "SELECT meta_key FROM $wpdb->postmeta WHERE meta_key = %s AND post_id = %d", $meta_key, $post_id ) ) )
                 return false;
 
-        $cache = wp_cache_get($post_id, 'post_meta');
-        if ( ! is_array($cache) )
-                $cache = array();
-        // expected_slashed ($meta_key)
-        $cache[$wpdb->escape($meta_key)][] = $meta_value;
-
-        wp_cache_set($post_id, $cache, 'post_meta');
-
         $meta_value = maybe_serialize($meta_value);
 
         $wpdb->insert( $wpdb->postmeta, compact( 'post_id', 'meta_key', 'meta_value' ) );
+
+        wp_delete_cache($post_id, 'post_meta');
+
         return true;
 }