From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from localhost (localhost [127.0.0.1]) by turing.freelists.org (Avenir Technologies Mail Multiplex) with ESMTP id 3A32E2F408 for ; Wed, 21 Nov 2018 13:58:49 -0500 (EST) Received: from turing.freelists.org ([127.0.0.1]) by localhost (turing.freelists.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id dWuVKKanuqVn for ; Wed, 21 Nov 2018 13:58:49 -0500 (EST) Received: from smtpng3.m.smailru.net (smtpng3.m.smailru.net [94.100.177.149]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by turing.freelists.org (Avenir Technologies Mail Multiplex) with ESMTPS id 81B342F406 for ; Wed, 21 Nov 2018 13:58:48 -0500 (EST) Date: Wed, 21 Nov 2018 21:58:42 +0300 From: Konstantin Osipov Subject: [tarantool-patches] Re: [PATCH 1/2] space: add method to fetch next rowid Message-ID: <20181121185842.GG18547@chai> References: <11f65a415a9b1101fa4ba816be237df524de9b47.1540838910.git.korablev@tarantool.org> <52d0faf6-598d-c29b-9b9d-50f4826573eb@tarantool.org> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Sender: tarantool-patches-bounce@freelists.org Errors-to: tarantool-patches-bounce@freelists.org Reply-To: tarantool-patches@freelists.org List-help: List-unsubscribe: List-software: Ecartis version 1.0.0 List-Id: tarantool-patches List-subscribe: List-owner: List-post: List-archive: To: tarantool-patches@freelists.org Cc: Vladislav Shpilevoy * n.pettik [18/11/12 16:12]: > > It is true that 2^64 is likely to be quite huge number of tuples, > but for instance JOIN uses nested-loop algorithm, so it requires > n^2 memory for ephemeral table to comprise results. > In this regard, to reach the limit we need 4-way join where each > table contains 2^16 entries, which in turn doesn’t seem to be giant. > > *It is only thoughts tho, I haven’t tested it since I suppose very likely > my pc would simply get stuck.* intel 64 bit architecture can not address more than 48 bits. Apart from the fact that you can multiply 4 numbers in a cross join there is a question how much time this nested loop is going to run. Imagine it runs 2^48 processor ticks. It's several weeks by a conservative estimate. > > I wanted to create long test as the easiest solution, but Alexander warned > me that Travis may not survive such test due to lack of memory. > > -- Konstantin Osipov, Moscow, Russia, +7 903 626 22 32 http://tarantool.io - www.twitter.com/kostja_osipov