Basically, you query the posts via query_posts first. WordPress has a global variable called $wp_query, which gets populated when you run query_posts().

So then when you run the usort on those posts, it sorts them. It’s inefficient since it’s getting all the posts from MySQL and then sorting them all in memory (which if you have a ton of posts would be veeery slow). But it works OK if you have a small number of posts.

In the example above, I am sorting by stars, and THEN within each block of the same number of stars, sorting by priority. You should be able to take the example tie-breaker function and adapt it to your needs.

Can you give an example of how this might work? In my case, I want to sort first by a custom field, and then alphabetically by post title within each “block” of posts of the custom field. I’m also not clear how the usort line is meant to integrate with a standard query_posts.

Thanks!

@chety: In the instance above, it would be a bit more complicated than just a simple hook into the posts_orderby hook, because there are also joins involved, so you’d also have to add the join into the join hook. But basically the idea is to use SQL to do the sorting for you before it returns the posts, instead of getting ALL the posts and then sorting them in memory, via the PHP code.

But if you were just ordering on two different standard fields (meaning, two fields both in the wp_posts table), in your SQL code the order clause would look something like ‘order by post_title, post_date’. The first column is the first one to sort on, and the second one will sort within the first sort.

E.g. Group A has 5 news stories from 11/17. Group B has 5 news stories from the day before (11/16).

Now, on the main archive page, the visitor would see these sorted by date descending.

But within each day, the posts would be sorted by a custom (sort_index) value.

Using the above method, im seeing the entire post list resorted according to this sort_index value. that is, it doesn’t seem to be double sorting but rather *re-sorting*.

Does this make sense? Am I way off base here?

Cheers, and thanks Jeff.