SELECT * FROM ( SELECT some_column, row_number() over (order by your_sort_column desc) as row_num FROM some_table ) t WHERE row_num = 3
If you expect more than one row to have the same value in your_sort_column
you can also use the rank() function
SELECT * FROM ( SELECT some_column, rank() over (order by your_sort_column desc) as row_rank FROM some_table ) t WHERE row_rank = 3
This migh return more than one row..