Re: Question about speed: Weird Behavior

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От Radosław Smogura
Тема Re: Question about speed: Weird Behavior
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Msg-id 1d5c89dfd44bddbdce2eff4e2287f66e@mail.softperience.eu
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Ответ на Re: Question about speed: Weird Behavior  (Samuel Gendler <sgendler@ideasculptor.com>)
Ответы Re: Question about speed: Weird Behavior  (Israel Ben Guilherme Fonseca <israel.bgf@gmail.com>)
Список pgsql-jdbc
 On Mon, 13 Jun 2011 21:44:45 -0700, Samuel Gendler wrote:
> On Mon, Jun 13, 2011 at 6:07 PM, Israel Ben Guilherme Fonseca  wrote:
>
>> When I use the count, my timings get around of
>>
>> 100 miliseconds.
>>
>> When I use the select it goes to
>>
>> 30 miliseconds.
>
> I dont know much about the internals of the protocol used to move
> data
> around for jdbc, but doesnt this actually make some sense?  If the
> query returns as soon as the first row has arrived, then select *
> should definitely be faster than select count(*), since count(*) cant
> return until the entire table has been scanned, whereas select *
> returns with the first row received.  That, at least, seems like a
> likely candidate for the difference between them, no?
>
> --sam
>
>
>
> Links:
> ------
> [1] mailto:israel.bgf@gmail.com
 Did you ran your queries in above order or did you changed order of
 queries. Please bear in mind, that if you set fetch size, then cursor
 approch will be used and not all data will be transferred to client
 side.

 Regards,
 Radek

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