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help / color / mirror / Atom feedFrom: Mariel Cherkassky <[email protected]>
To: Andreas Kretschmer <[email protected]>
Cc: [email protected]
Subject: Re: select with max functions
Date: Mon, 2 Oct 2017 16:25:19 +0300
Message-ID: <CA+t6e1=9if3_zd734XkBFY7xiS_OosE2t9sSK3JgPav_E9RgNA@mail.gmail.com> (raw)
In-Reply-To: <[email protected]>
References: <CA+t6e1mVtJveyoRRW8fLzY0tJhXntLrYxpSrk0=dDH8q93VPEA@mail.gmail.com>
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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 <[email protected]>:
>
>
> 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
>
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