Postgres SELECT DISTINCT, only highest values [duplicate]

Question

I am using the following pgsql query to select index_id and making a distinct query on the level column.

SELECT DISTINCT ON (level) index_id FROM indexes 

Although its working, it is returning the first index_id for each level, i would like to get the highest index_id in each distinct level

Answer 1

Use order by to get the max index_id

SELECT DISTINCT ON (level) index_id 
FROM indexes 
order by level, index_id desc

Answer 2

Try tou use GROUP BY instead of DISTINCT ON

SELECT MAX(index_id)  FROM indexes GROUP BY level