Defining post_status or post_type

By default, the post_status of a query is set to publish for anonymous users on the front end. It is not set in any WP_ADMIN context, including Ajax queries.

Queries on the front end for logged-in users will also contain an OR statement for private posts created by the logged-in user, even if that user is not part of the site. This will reduce the effectiveness of MySQL indexes, specifically the type_status_date index.

The same is true for post_type. If it is known that only a certain post_type will match the rest of the query (for example, for a taxonomy, meta, or just a general query), adding the post_type as well as the post_status will help MySQL better utilize the indexes at its disposal.