RANK is a good example of a useful less known window function. Please also consider dense_rank and row_number. All 3 have their advantages and disadvantages...

RANK is a good example of a useful less known window function. Please also consider dense_rank and row_number. All 3 have their advantages and disadvantages... (Rank leaves holes after rows with the same order, dense_rank gives consecutive numbers, row_number just numbers the rows.)