Re: SeqScan costs

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От Decibel!
Тема Re: SeqScan costs
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Msg-id 0EF13902-9E3F-4FE1-BE12-A05116FF2644@decibel.org
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Ответ на Re: SeqScan costs  (Tom Lane <tgl@sss.pgh.pa.us>)
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On Aug 18, 2008, at 11:49 AM, Tom Lane wrote:
>> Perhaps what's also needed here is to measure just how accurate  
>> the cpu_*
>> costs are. Perhaps they need to be raised somewhat if we're  
>> underestimating
>> the cost of digging through 200 tuples on a heap page and the  
>> benefit of a
>> binary search on the index tuples.
>
> Possibly.  I doubt anyone's ever taken a hard look at the cpu_xxx
> values.


Josh Berkus indicated at PGCon that he's had luck *decreasing* the  
CPU costs, but IIRC that was mostly on OLAP systems. It seems we need  
some real data here.
-- 
Decibel!, aka Jim C. Nasby, Database Architect  decibel@decibel.org
Give your computer some brain candy! www.distributed.net Team #1828



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