Return-Path: X-Original-To: apmail-hive-user-archive@www.apache.org Delivered-To: apmail-hive-user-archive@www.apache.org Received: from mail.apache.org (hermes.apache.org [140.211.11.3]) by minotaur.apache.org (Postfix) with SMTP id 9157EDB67 for ; Mon, 15 Oct 2012 13:11:53 +0000 (UTC) Received: (qmail 87656 invoked by uid 500); 15 Oct 2012 13:11:52 -0000 Delivered-To: apmail-hive-user-archive@hive.apache.org Received: (qmail 87133 invoked by uid 500); 15 Oct 2012 13:11:46 -0000 Mailing-List: contact user-help@hive.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: user@hive.apache.org Delivered-To: mailing list user@hive.apache.org Received: (qmail 87103 invoked by uid 99); 15 Oct 2012 13:11:45 -0000 Received: from athena.apache.org (HELO athena.apache.org) (140.211.11.136) by apache.org (qpsmtpd/0.29) with ESMTP; Mon, 15 Oct 2012 13:11:45 +0000 X-ASF-Spam-Status: No, hits=-0.5 required=5.0 tests=FREEMAIL_ENVFROM_END_DIGIT,RCVD_IN_DNSWL_LOW,SPF_PASS X-Spam-Check-By: apache.org Received-SPF: pass (athena.apache.org: domain of liy099@gmail.com designates 209.85.210.176 as permitted sender) Received: from [209.85.210.176] (HELO mail-ia0-f176.google.com) (209.85.210.176) by apache.org (qpsmtpd/0.29) with ESMTP; Mon, 15 Oct 2012 13:11:40 +0000 Received: by mail-ia0-f176.google.com with SMTP id h11so4270174iae.35 for ; Mon, 15 Oct 2012 06:11:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :content-type; bh=PwqwWuNnju8rk4Bre5rLkspa+qXiqScDfhs/kK+A3Xc=; b=MIVGHhtQFMZleGMBDZG1bzRVMwA++y5C9SCIcVcT2+Ha0Kad+/LvSsu7l8/dlrxW7c tSv/u2EsS+wIqlzen5nnooDDPnmkMwWBqnsQUFNp/uWWVdz0zWstr6dDMw1IWB+WP2mf lnE+ZMgQQtqyx5PnkkE9K8HNc1wemgna2zX5dH8o+jfCIiSCx8IVToBnEh/tt4WyStMk 05pS85BBrFoAZZovB/EkhLVrIq2hgrYc72vcRbMnC9D3gD9UdZKyVCN9Y3Fr5WsoRaG1 mVfRXVY4qxYBZR3xTbT2SMWCHYqwqoaKfXRnK7qUbbsu4fwqmxVLXDK+KmcVTztPUFc2 BADw== Received: by 10.50.158.201 with SMTP id ww9mr8795238igb.22.1350306679757; Mon, 15 Oct 2012 06:11:19 -0700 (PDT) MIME-Version: 1.0 Received: by 10.64.38.132 with HTTP; Mon, 15 Oct 2012 06:10:39 -0700 (PDT) In-Reply-To: References: From: MiaoMiao Date: Mon, 15 Oct 2012 21:10:39 +0800 Message-ID: Subject: Re: Hive Query Unable to distribute load evenly in reducers To: user@hive.apache.org Content-Type: text/plain; charset=UTF-8 X-Virus-Checked: Checked by ClamAV on apache.org And your queries were? On Mon, Oct 15, 2012 at 8:09 PM, Saurabh Mishra wrote: > Hi, > I am firing some hive queries joining tables containing upto 30millions > records each. Since the load on the reducers is very significant in these > cases, i specifically set the following parameters before executing the > queries : > > set mapred.reduce.tasks=100; > set hive.exec.reducers.bytes.per.reducer=500000000; > set hive.optimize.cp=true; > > The number of reducer the job spouts in now 160, but despite the high number > most of the load remains upon 1 or 2 reducers. Hence in the final > statistics, 158 reducers go completed with 2-3 minutes of start and 2 > reducers took 2 hrs to run. > Is there any way to overcome this load distribution disparity. > Any help in this regards will be highly appreciated. > > Sincerely > Saurabh Mishra