Getting Error while using row_number()

I have environment with PostgreSQL 8.0.2 on i686-pc-linux-gnu and I am trying to write sql syntax like mentioned below and getting mentioned below. 

select distinct journey_id
, ROW_NUMBER OVER (partition by `journey_id` ORDER BY journey_id)
from table_name

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 `journey_id` ORDER BY `journey_id`) from `consents` limit 10' at line 6  

Kindly advise asap

Thanks 

Ashish Kaushal

8285877270