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Re: Speed with offset clause

From: Yves Vindevogel <yves(dot)vindevogel(at)implements(dot)be>
To: pgsql-performance(at)postgresql(dot)org
Subject: Re: Speed with offset clause
Date: 2005-06-24 20:34:52
Message-ID: 9be37ba2f850707ad5db17162c56cd64@implements.be (view raw or flat)
Thread:
Lists: pgsql-performance
I just ran this query

select p.* from tblPrintjobs p , (select oid from tblPrintjobs limit 25 
offset 622825) as subset where p.oid = subset.oid

And it seems to be a bit faster than without the subselect, probably 
because I'm only getting one column.
The speed gain is not that high though

On 24 Jun 2005, at 22:19, Yves Vindevogel wrote:

>>
>> Hmm, I can't do this, i'm afraid.  Or it would be rather difficult
>>
>> My query is executed through a webpage (link to the page in a 
>> navigation bar)
>> I do not know how many records there are (data is changing, and 
>> currently is 600k records)
>>
>> The only thing I could do, is doing this in a function where I first 
>> get the page, and then decide whether to use the normal sort order or 
>> the reversed order
>> That would put my weak point right in the middle, which is not that 
>> bad, but I would like to find an easier way, if that is possible
>>
>> Huge memory would help ?
>>
>> On 24 Jun 2005, at 20:54, hubert depesz lubaczewski wrote:
>>
>>> On 6/24/05, Yves Vindevogel <yves(dot)vindevogel(at)implements(dot)be> wrote:
>>>> So, when I want the last page, which is: 600k / 25 = page 24000 - 1 
>>>> =
>>>> 23999, I issue the offset of 23999 * 25
>>>
>>> improving this is hard, but not impossible.
>>> if you have right index created, try to reverse the order and fetch
>>> first adverts, and then resort it (just the 25 adverts) in correct
>>> order.
>>> it will be faster.
>>>
>>> depesz
>>>
>>>
>> Met vriendelijke groeten,
>> Bien à vous,
>> Kind regards,
>>
>> Yves Vindevogel
>> Implements
>>
> <Pasted Graphic 2.tiff>
>>
>> Mail: yves(dot)vindevogel(at)implements(dot)be  - Mobile: +32 (478) 80 82 91
>>
>> Kempische Steenweg 206 - 3500 Hasselt - Tel-Fax: +32 (11) 43 55 76
>>
>> Web: http://www.implements.be
>>
>> First they ignore you.  Then they laugh at you.  Then they fight you. 
>>  Then you win.
>> Mahatma Ghandi.
>>
>>
> Met vriendelijke groeten,
> Bien à vous,
> Kind regards,
>
> Yves Vindevogel
> Implements
>
> <Pasted Graphic 2.tiff>
>
> Mail: yves(dot)vindevogel(at)implements(dot)be  - Mobile: +32 (478) 80 82 91
>
> Kempische Steenweg 206 - 3500 Hasselt - Tel-Fax: +32 (11) 43 55 76
>
> Web: http://www.implements.be
>
> First they ignore you.  Then they laugh at you.  Then they fight you.  
> Then you win.
> Mahatma Ghandi.
>
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Met vriendelijke groeten,
Bien à vous,
Kind regards,

Yves Vindevogel
Implements


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Subject: Re: Needed: Simplified guide to optimal memory configuration
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Subject: Re: Speed with offset clause

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