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To: "Zeugswetter Andreas SB SD" <ZeugswetterA@spardat.at>
cc: "Tom Lane" <tgl@sss.pgh.pa.us>, pgsql-hackers@postgresql.org
Subject: Re: again on index usage 
In-reply-to: Your message of "Thu, 10 Jan 2002 11:55:20 +0100."
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Date: Thu, 10 Jan 2002 13:37:41 +0200
From: Daniel Kalchev <daniel@digsys.bg>
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>>>"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