On Thu, 26 Feb 2004, Dror Matalon wrote: > Hi, > > We have postgres running on freebsd 4.9 with 2 Gigs of memory. As per > repeated advice on the mailing lists we configured effective_cache_size > = 25520 which you get by doing `sysctl -n vfs.hibufspace` / 8192 > > Which results in using 200Megs for disk caching. > > Is there a reason not to increase the hibufspace beyond the 200 megs and > provide a bigger cache to postgres? I looked both on the postgres and > freebsd mailing lists and couldn't find a good answer to this.
Actually, I think you're confusing effective_cache_size with shared_buffers. effective_cache_size changes no cache settings for postgresql, it simply acts as a hint to the planner on about how much of the dataset your OS / Kernel / Disk cache can hold. Making it bigger only tells the query planny it's more likely the data it's looking for will be in cache. shared_buffers, OTOH, sets the amount of cache that postgresql uses. It's generall considered that 256 Megs or 1/4 of memory, whichever is LESS, is a good setting for production database servers. ---------------------------(end of broadcast)--------------------------- TIP 3: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly