WP_Query multiple use of relation and/or

No, meta_query does not support these sorts of complex clauses in a sequence.

There are a couple of ways to work around this limitation.

• One is to filter posts_where_paged and modify the SQL manually. I just spent a couple minutes playing with this option, and it’s not very straightforward – you’ll have to write a pretty sophisticated preg_replace() to get the parentheses grouped right, etc.

• A more promising option is to get a whitelist of post ids manually, and then feed the results to the post__in parameter of WP_Query:

  global $wpdb;
  $post_ids = $wpdb->get_col( $wpdb->prepare( "
      SELECT post_id 
      FROM $wpdb->postmeta.pm 
      INNER JOIN $wpdb->postmeta.pm2 ON (pm.post_id = pm2.post_id)
      WHERE
          (pm.meta_key = 'status' AND pm.meta_value="1" 
          AND pm2.meta_key = 'start_date' AND pm2.meta_value >= '1332115200')
      OR
          (pm.meta_key = 'status' AND pm.meta_value="2")
  " ) );
  
  $query_args = array( 'post__in' => $post_ids ); // plus whatever else you want
  $my_query = new WP_Query( $query_args );
  

  When WP_Query assembles the SQL, your $post_ids get turned into a clause like: AND ID IN (1,2,3), which acts like a whitelist for whatever other parameters you pass to WP_Query.

Note that either way, this query is not going to be all that fast, since it requires some loose type casting on unindexed meta_value. Cache wisely 🙂