Received: from localhost (unknown [200.46.204.184]) by developer.postgresql.org (Postfix) with ESMTP id BC0B92E010C for ; Thu, 3 Apr 2008 14:49:12 -0300 (ADT) Received: from developer.postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.184]) (amavisd-maia, port 10024) with ESMTP id 65554-02 for ; Thu, 3 Apr 2008 14:48:58 -0300 (ADT) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.5 Received: from wa-out-1112.google.com (wa-out-1112.google.com [209.85.146.183]) by developer.postgresql.org (Postfix) with ESMTP id 057542E00C0 for ; Thu, 3 Apr 2008 14:48:59 -0300 (ADT) Received: by wa-out-1112.google.com with SMTP id m38so3640857waf.5 for ; Thu, 03 Apr 2008 10:48:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=beta; h=domainkey-signature:received:received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; bh=ue2ZbElcSxaJZjnZl5Filj2Ccr+3njttVj94VP8I+E4=; b=TMuQpAaqP8cqN+Usm5p9FugrnhQnFDjQMq4x6pdDquYhYhVAyJNq/+/SY5lh+xOFNcR0UXJk2C5dyV6aus3k18sKJhAUud3+5VCrTg9Pb7bLm1utSySpioPTS5Wu8VJZagK6qrKIp+g1sfO6o8gN73jso/X7BdYiy52qB2jj1K0= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=MA35G4PDwb+fLn0m2rdhNsd/sA7Xdl9tY233yNZJcdAntvzr4JsgBAPYHtXy64JkWn+W8yY37OURCJUYGnINeYbzF5kP7ojT69pwKpyawjwlsdFw+uxxteUFdvQ0x9QeCfE+32Yqzio4uZc7oOBRZwRX7OTvqwJjkqQEdiqcN1I= Received: by 10.114.60.19 with SMTP id i19mr172248waa.106.1207244938800; Thu, 03 Apr 2008 10:48:58 -0700 (PDT) Received: by 10.114.137.7 with HTTP; Thu, 3 Apr 2008 10:48:58 -0700 (PDT) Message-ID: Date: Thu, 3 Apr 2008 11:48:58 -0600 From: "Scott Marlowe" To: "Andrej Ricnik-Bay" Subject: Re: Max shared_buffers Cc: "sathiya psql" , bitaoxiao , "pgsql-performance@postgresql.org" In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <47F324B4.6010404@mansionfamily.plus.com> <200804031256103599734@gmail.com> X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200804/36 X-Sequence-Number: 29529 On Thu, Apr 3, 2008 at 11:16 AM, Andrej Ricnik-Bay wrote: > On 04/04/2008, Scott Marlowe wrote: > > Not entirely true. on 32 bit OS / software, the limit is just under 2 > > Gig. > > Where do you get that figure from? > > There's an architectural (theoretical) limitation of RAM at 4GB, > but with the PAE (that pretty much any CPU since the Pentium Pro > offers) one can happily address 64GB on 32-bit. > > Or are you talking about some Postgres limitation? Note I was talking about running 32 bit postgresql (on either 32 or 64 bit hardware, it doesn't matter) where the limit we've seen in the perf group over the years has been just under 2G. I'm extrapolating that on 64 bit hardware, 64 bit postgresql's limit would be similar, i.e. 2^63-x where x is some small number that keeps us just under 2^63. So, experience and reading here for a few years is where I get that number from. But feel free to test it. It'd be nice to know you could get >2Gig shared buffer on 32 bit postgresql on some environment.