Am 01.10.2017 um 14:41 schrieb Mariel Cherkassky:
I need to use the max function in my query. I had very bad performance when I used the max :

               SELECT Ma.User_Id,
                      COUNT(*) COUNT
               FROM   Manuim Ma
               WHERE  Ma.Bb_Open_Date  =
                                  (SELECT max(Bb_Open_Date)
                                   FROM  Manuim Man
                                   WHERE Man.User_Id = Ma.User_Id
               GROUP  BY Ma.User_Id
               HAVING COUNT(*) > 1;

Any idea how can I continue from here ? Thanks , Mariel.

Maybe you can rewrite it, for instance to

select distinct on (user_id, bb_open_date) user_id, bb_open_date, count(1) from Manuim group by 1,2 having count(1) > 1;

maybe much cheaper, but untested! If not, please share more details, at least table-definition.

Regards, Andreas

2ndQuadrant - The PostgreSQL Support Company.

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