WordPress at a glance
function is not described

Automattic\WooCommerce\Admin\API

Products::add_wp_query_group_by() public WC 1.0

Group by post ID to prevent duplicates.

{} It's a method of the class: Products{}

No Hooks.

Return

String. Nothing.

Usage

$result = Products::add_wp_query_group_by( $groupby, $wp_query );
$groupby(string) (required)
Group by clause used to organize posts.
$wp_query(object) (required)
WP_Query object.

Code of Products::add_wp_query_group_by() WC 5.3.0

<?php
public static function add_wp_query_group_by( $groupby, $wp_query ) {
	global $wpdb;

	$search       = $wp_query->get( 'search' );
	$low_in_stock = $wp_query->get( 'low_in_stock' );
	if ( empty( $groupby ) && ( $search || $low_in_stock ) ) {
		$groupby = $wpdb->posts . '.ID';
	}
	return $groupby;
}