ROW_NUMBER() no MySQL

Boa tarde!

Como faço o ROW_NUMBER() funcionar no MySQL? No manual tem essa estrutura mas não dá certo.

SELECT
ID_METRICA_VALOR
, NU_VALOR
, FK_METRICA
, DH_ATUALIZACAO
, ROW_NUMBER() OVER(PARTITION BY ID_METRICA_VALOR ORDER BY NU_VALOR) AS row_num2
FROM TB_METRICA_VALOR
WHERE FK_METRICA = 9
ORDER BY NU_VALOR DESC

Segue o erro:

[Code: 1064, SQL State: 42000] You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '(PARTITION BY FK_METRICA ORDER BY NU_VALOR) AS row_num2
FROM TB_METRICA_VALOR
’ at line 6

Grato