Date: Mon, 14 Mar 2005 10:07:08 +0100 (CET) From: Claus Guttesen <cguttesen@yahoo.dk> To: freebsd-performance@freebsd.org Subject: postgresql, max_fsm_pages on FreeBSD 5.3 Message-ID: <20050314090708.4219.qmail@web26805.mail.ukl.yahoo.com>
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Hi. I'm running a postgresql 7.4.6 db, where the largest table having 13 mill. records. The db-server is a quad-opteron with 4 GB RAM. I've configured shared_buffers to 8192, sort_mem to 4096 and effective_cache_size to 4096. max_fsm_relations and max_fsm_pages was easy to configure when I found http://www.desknow.com/kb/idx/12/061/article/ (max_fsm_pages and max_fsm_relations). The odd thing is that according to a vacuum verbose where total pages needed always seems to be approx. 15.000 pages larger than what max_fsm_pages is configured to. So I keept increasing max_fsm_pages, from 60000, 80000 and now 100000. This morning my beloved crontab send me a verbose vacuum telling me "114848 total pages needed". max_fsm_relations remains steady at 300 (245 relations according to the output). Not that I mind increasing this value, but is there any limit to this value, or will I reach some thresshold where this setting will become counterproductive? The docs says that max_fsm_pages "Sets the maximum number of disk pages for which free space will be tracked in the shared free-space map." But what does that actually mean? Postgresql does seem to perform better when I tweak max_fsm_pages. The above mentioned shared buffers, sort mem and effective cache size did become counterproductive when I increased them too much. regards Claus
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