WordPress at a glance
filter is not described

posts_request filter-hook . WP 2.0.0

Filters the completed SQL query before sending.

Usage

add_filter( 'posts_request', 'filter_function_name_8065', 10, 2 );
function filter_function_name_8065( $request, $this ){
	// filter...

	return $request;
}
$request(string)
The complete SQL query.
$this(WP_Query)
The WP_Query instance (passed by reference).

Where the hook is called

WP_Query::get_posts()
posts_request
wp-includes/class-wp-query.php 2737
$this->request = apply_filters_ref_array( 'posts_request', array( $this->request, &$this ) );

Where the hook is used (in WP core)

Does not used.