WordPress File wp-includes/class-wp-query.php

posts_results

Filters the raw post results array, prior to status checks.

posts_search

Filters the search SQL that is used in the WHERE clause of WP_Query.

posts_selection

Fires to announce the query’s current selection parameters.

pre_get_posts

Fires after the query variable object is created, but before the actual query is run.

set_404

Fires after a 404 is triggered.