Return-Path: Delivered-To: apmail-couchdb-user-archive@www.apache.org Received: (qmail 71301 invoked from network); 6 Feb 2009 07:45:16 -0000 Received: from hermes.apache.org (HELO mail.apache.org) (140.211.11.2) by minotaur.apache.org with SMTP; 6 Feb 2009 07:45:16 -0000 Received: (qmail 61572 invoked by uid 500); 6 Feb 2009 07:45:13 -0000 Delivered-To: apmail-couchdb-user-archive@couchdb.apache.org Received: (qmail 61546 invoked by uid 500); 6 Feb 2009 07:45:13 -0000 Mailing-List: contact user-help@couchdb.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: user@couchdb.apache.org Delivered-To: mailing list user@couchdb.apache.org Received: (qmail 61535 invoked by uid 99); 6 Feb 2009 07:45:13 -0000 Received: from athena.apache.org (HELO athena.apache.org) (140.211.11.136) by apache.org (qpsmtpd/0.29) with ESMTP; Thu, 05 Feb 2009 23:45:13 -0800 X-ASF-Spam-Status: No, hits=-0.0 required=10.0 tests=SPF_PASS X-Spam-Check-By: apache.org Received-SPF: pass (athena.apache.org: domain of b.candler@pobox.com designates 208.72.237.25 as permitted sender) Received: from [208.72.237.25] (HELO sasl.smtp.pobox.com) (208.72.237.25) by apache.org (qpsmtpd/0.29) with ESMTP; Fri, 06 Feb 2009 07:45:05 +0000 Received: from localhost.localdomain (unknown [127.0.0.1]) by b-sasl-quonix.sasl.smtp.pobox.com (Postfix) with ESMTP id 7D91C2A8B2; Fri, 6 Feb 2009 02:44:40 -0500 (EST) Received: from mappit (unknown [80.45.95.114]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by b-sasl-quonix.sasl.smtp.pobox.com (Postfix) with ESMTPSA id 20CFE2A8B0; Fri, 6 Feb 2009 02:44:39 -0500 (EST) Received: from brian by mappit with local (Exim 4.69) (envelope-from ) id 1LVLO9-0003zL-Dm; Fri, 06 Feb 2009 07:44:37 +0000 Date: Fri, 6 Feb 2009 07:44:37 +0000 From: Brian Candler To: Chris Anderson Cc: user@couchdb.apache.org Subject: Re: Penalty for reduce? Message-ID: <20090206074437.GA15275@uk.tiscali.com> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17+20080114 (2008-01-14) X-Pobox-Relay-ID: 02DB6EFE-F422-11DD-872D-6F7C8D1D4FD0-28021239!a-sasl-quonix.pobox.com X-Virus-Checked: Checked by ClamAV on apache.org On Thu, Feb 05, 2009 at 07:09:15PM -0800, Chris Anderson wrote: > On Thu, Feb 5, 2009 at 12:38 PM, Brian Candler wrote: > > I'm just wondering, how much is the performance penalty for adding reduce to > > a view? In other words, is there any reason *not* to include a reduce > > I'm not sure. It would be a simple matter to add log() statements to a > reduce function to see if it is run during map queries or if it is > only run when reduce=true. I was also wondering how much penalty there is when the view is being updated. (I would expect not much - I understand the reduce value is stored in each interior b-tree node, so would only have to be recalculated for those nodes which have changed, but wanted a second opinion)