_update_post_term_count

/**
 * Add count of children to parent count.
 *
 * Recalculates term counts by including items from child terms. Assumes all
 * relevant children are already in the $terms argument.
 *
 * @access private
 * @since 2.3.0
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param array  $terms    List of term objects (passed by reference).
 * @param string $taxonomy Term context.
 */
function _pad_term_counts( &$terms, $taxonomy ) {
	global $wpdb;

	// This function only works for hierarchical taxonomies like post categories.
	if ( ! is_taxonomy_hierarchical( $taxonomy ) ) {
		return;
	}

	$term_hier = _get_term_hierarchy( $taxonomy );

	if ( empty( $term_hier ) ) {
		return;
	}

	$term_items  = array();
	$terms_by_id = array();
	$term_ids    = array();

	foreach ( (array) $terms as $key => $term ) {
		$terms_by_id[ $term->term_id ]       = & $terms[ $key ];
		$term_ids[ $term->term_taxonomy_id ] = $term->term_id;
	}

	// Get the object and term IDs and stick them in a lookup table.
	$tax_obj      = get_taxonomy( $taxonomy );
	$object_types = esc_sql( $tax_obj->object_type );
	$results      = $wpdb->get_results( "SELECT object_id, term_taxonomy_id FROM $wpdb->term_relationships INNER JOIN $wpdb->posts ON object_id = ID WHERE term_taxonomy_id IN (" . implode( ',', array_keys( $term_ids ) ) . ") AND post_type IN ('" . implode( "', '", $object_types ) . "') AND post_status = 'publish'" );