Here’s what I ended up with, and it seems to work.
$upcoming_query = new WP_Query(array(
'post_type' => 'my_event',
'numberposts' => -1,
'posts_per_page' => 1000000,
'meta_query' => array(
'relation' => 'AND',
'start_date_clause' => array(
'key' => 'start_date',
'value' => Carbon::now()->format("Ymd"),
'compare' => '>=',
),
'same_date_sort_clause' => array(
'key' => 'same_date_sort', // higher number is earlier
'compare' => 'EXISTS',
),
),
'orderby' => array(
'start_date_clause' => "DESC",
'same_date_sort_clause' => "ASC"
)
));
The same_date_sort/EXISTS clause doesn’t do anything (they all have that field), but it lets me use same_date_sort_clause/ASC for sorting below.
