Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtp (Exim 4.80) (envelope-from ) id 1Vpwz5-0000T2-Kh for pgsql-hackers@arkaria.postgresql.org; Mon, 09 Dec 2013 09:18:35 +0000 Received: from localhost ([127.0.0.1] helo=postgresql.org) by malur.postgresql.org with smtp (Exim 4.80) (envelope-from ) id 1Vpwz4-0004TL-Vr for pgsql-hackers@arkaria.postgresql.org; Mon, 09 Dec 2013 09:18:35 +0000 Received: from magus.postgresql.org ([2a02:c0:301:0:ffff::29]) by malur.postgresql.org with esmtp (Exim 4.80) (envelope-from ) id 1Vpwz2-0004TA-Jt for pgsql-hackers@postgresql.org; Mon, 09 Dec 2013 09:18:32 +0000 Received: from smtp-outbound-2.vmware.com ([208.91.2.13]) by magus.postgresql.org with esmtp (Exim 4.80) (envelope-from ) id 1Vpwyq-0005X3-Q3 for pgsql-hackers@postgresql.org; Mon, 09 Dec 2013 09:18:31 +0000 Received: from sc9-mailhost2.vmware.com (sc9-mailhost2.vmware.com [10.113.161.72]) by smtp-outbound-2.vmware.com (Postfix) with ESMTP id B9BDA2A586; Mon, 9 Dec 2013 01:18:16 -0800 (PST) Received: from zcs-prod-ext-mta-1.vmware.com (zcs-prod-ext-mta-1.vmware.com [10.113.62.223]) by sc9-mailhost2.vmware.com (Postfix) with ESMTP id B0149B03AF; Mon, 9 Dec 2013 01:18:16 -0800 (PST) Received: from zcs-prod-ext-mta-1.vmware.com (localhost.localdomain [127.0.0.1]) by zcs-prod-ext-mta-1.vmware.com (Postfix) with ESMTP id A313D12002F; Mon, 9 Dec 2013 01:18:47 -0800 (PST) Received: from [192.168.1.90] (zimbra-prod-ext-proxy-vip.vmware.com [10.113.63.87]) by zcs-prod-ext-mta-1.vmware.com (Postfix) with ESMTPSA; Mon, 9 Dec 2013 01:18:46 -0800 (PST) Message-ID: <52A58AD5.6030808@vmware.com> Date: Mon, 09 Dec 2013 11:18:13 +0200 From: Heikki Linnakangas Organization: VMware User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20131005 Icedove/17.0.9 MIME-Version: 1.0 To: Alexander Korotkov CC: Alvaro Herrera , Tomas Vondra , pgsql-hackers Subject: Re: GIN improvements part 1: additional information References: <524E7C3B.7060402@vmware.com> <5250A7A1.2010701@fuzzy.cz> <52546434.1000303@vmware.com> <52548F79.6030407@fuzzy.cz> <52569635.5090808@vmware.com> <527A03AF.9010501@vmware.com> <20131106153604.GM5809@eldon.alvh.no-ip.org> <528CEB34.7080702@vmware.com> <52950F46.2080009@vmware.com> <5298615C.7060102@vmware.com> <5298E834.4090408@vmware.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Pg-Spam-Score: -6.9 (------) List-Archive: List-Help: List-ID: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: X-Mailing-List: pgsql-hackers Precedence: bulk Sender: pgsql-hackers-owner@postgresql.org On 12/08/2013 09:56 PM, Alexander Korotkov wrote: > On Fri, Nov 29, 2013 at 11:17 PM, Heikki Linnakangas < > hlinnakangas@vmware.com> wrote: > >> I'll continue reviewing next week.. Got dragged into other things and didn't make any progress on this last week. I'm trying again now. > Good. Thanks for debug and fixing bugs. > Can I do anything for this patch now? I wonder if we're leaving some money on the table, by using varbyte encoding. Googling around, there are many other compression methods out there for compressing integer deltas that compress better, and/or decompress faster. Even if we use varbyte encoding, I wonder if it would be better to treat block + offset number as a single 48-bit integer, rather than encode them separately. That would allow the delta of two items on the same page to be stored as a single byte, rather than two bytes. Naturally it would be a loss on other values, but would be nice to see some kind of an analysis on that. I suspect it might make the code simpler, too. - Heikki -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers