| From: | Mark Kirkwood <markir(at)paradise(dot)net(dot)nz> |
|---|---|
| To: | Merlin Moncure <merlin(dot)moncure(at)rcsonline(dot)com> |
| Cc: | pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Hardware/OS recommendations for large databases ( |
| Date: | 2005-11-28 21:45:46 |
| Message-ID: | 438B7A8A.4020505@paradise.net.nz |
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| Lists: | pgsql-performance |
Merlin Moncure wrote:
>>It certainly makes quite a difference as I measure it:
>>
>>doing select(1) from a 181000 page table (completely uncached) on my
>
> PIII:
>
>>8.0 : 32 s
>>8.1 : 25 s
>>
>>Note that the 'fastcount()' function takes 21 s in both cases - so all
>>the improvement seems to be from the count overhead reduction.
>
>
> Are you running windows? There is a big performance improvement in
> count(*) on pg 8.0->8.1 on win32 that is not relevant to this debate...
>
No - FreeBSD 6.0 on a dual PIII 1 Ghz. The slow cpu means that the 8.1
improvements are very noticeable!
A point of interest - applying Niels palloc - avoiding changes to
NodeAgg.c and int8.c in 8.0 changes those results to:
8.0 + palloc avoiding patch : 27 s
(I am guessing the remaining 2 s could be shaved off if I backported
8.1's virtual tuples - however that looked like a lot of work)
Cheers
Mark
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