apart from the predefined where clause, it needs somehow to be able to support passing a string containing a filter clause that it's parameters are already resolved prior to the Query function, I proposed a possible solution to be able to declare in the sql definition something like this

-- name: ListOrders :many  select * from order where status = $1 and (@filter::text);

Generated

const listOrders = "select * from order where status = $1 and (@filter::text);"

 type ListOrdersParams struct {       Status string       Filter string}

func (q *Queries) ListOrders(ctx context.Context, arg ListOrdersParams) ([]*ListOrdersRow, error) {        filter:=arg.Filter        if filter=="" {           filter = "1=1"        }        listOrdersWithFilter = strings.Replace(listOrders, "@filter::text", filter, -1)rows, err := q.db.Query(ctx, listOrdersWithFilter, arg.Status)...

What database engines need to be changed?

PostgreSQL, MySQL

What programming language backends need to be changed?

Go, Python, Kotlin