Re: select with max functions

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Andreas I tried to rewrite it with the function rank() but I failed. The query you wrote isnt the same as what I search. Moreover, I cant use explain analyze because it is taking to much time to run and I'm getting timeout..

2017-10-01 21:48 GMT+03:00 Andreas Kretschmer <andreas@xxxxxxxxxxxxxxx>:


Am 01.10.2017 um 14:41 schrieb Mariel Cherkassky:
Hi,
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.
www.2ndQuadrant.com



--
Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-performance


[Postgresql General]     [Postgresql PHP]     [PHP Users]     [PHP Home]     [PHP on Windows]     [Kernel Newbies]     [PHP Classes]     [PHP Books]     [PHP Databases]     [Yosemite]

  Powered by Linux