| From: | Daniel Kalchev <daniel(at)digsys(dot)bg> |
|---|---|
| To: | "Zeugswetter Andreas SB SD" <ZeugswetterA(at)spardat(dot)at> |
| Cc: | "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: again on index usage |
| Date: | 2002-01-10 11:37:41 |
| Message-ID: | 200201101137.NAA00235@dcave.digsys.bg |
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| Lists: | pgsql-hackers |
>>>"Zeugswetter Andreas SB SD" said:
> What is actually estimated wrong here seems to be the estimated
> effective cache size, and thus the cache ratio of page fetches.
> Most of your pages will be cached.
>
> The tuning parameter is: effective_cache_size
>
> With (an estimated) 50 % of 512 Mb for file caching that number would
> need to be:
> effective_cache_size = 32768 # 8k pages
>
> Can you try this and tell us what happens ?
I suspected this, but haven't really come to test it. On BSD/OS, the buffer
cache is 10% of the RAM, in my case
buffer cache = 53522432 (51.04 MB)
I guess effective_cache_size = 6400 will be ok.
Daniel
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