This method fetches the next set of rows of a query results, returning a list of tuples. An empty list is returned when no more rows are available.
The number of rows returned can be specified using the size argument, which defaults to one. Fewer rows might be returned, when there are not more rows available than specified by the argument.
Note that you must fetch all rows before being able to execute new queries using the same connection.
Returns a list of tuples or empty list when no rows available.