Return-Path: X-Original-To: apmail-hive-dev-archive@www.apache.org Delivered-To: apmail-hive-dev-archive@www.apache.org Received: from mail.apache.org (hermes.apache.org [140.211.11.3]) by minotaur.apache.org (Postfix) with SMTP id 3A44FC349 for ; Tue, 16 Jul 2013 14:32:51 +0000 (UTC) Received: (qmail 43063 invoked by uid 500); 16 Jul 2013 14:32:50 -0000 Delivered-To: apmail-hive-dev-archive@hive.apache.org Received: (qmail 42992 invoked by uid 500); 16 Jul 2013 14:32:50 -0000 Mailing-List: contact dev-help@hive.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: dev@hive.apache.org Delivered-To: mailing list dev@hive.apache.org Received: (qmail 42912 invoked by uid 500); 16 Jul 2013 14:32:49 -0000 Delivered-To: apmail-hadoop-hive-dev@hadoop.apache.org Received: (qmail 42907 invoked by uid 99); 16 Jul 2013 14:32:49 -0000 Received: from arcas.apache.org (HELO arcas.apache.org) (140.211.11.28) by apache.org (qpsmtpd/0.29) with ESMTP; Tue, 16 Jul 2013 14:32:49 +0000 Date: Tue, 16 Jul 2013 14:32:49 +0000 (UTC) From: "Brock Noland (JIRA)" To: hive-dev@hadoop.apache.org Message-ID: In-Reply-To: References: Subject: [jira] [Updated] (HIVE-4113) Optimize select count(1) with RCFile and Orc MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-JIRA-FingerPrint: 30527f35849b9dde25b450d4833f0394 [ https://issues.apache.org/jira/browse/HIVE-4113?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ] Brock Noland updated HIVE-4113: ------------------------------- Status: Open (was: Patch Available) Cancelling patch > Optimize select count(1) with RCFile and Orc > -------------------------------------------- > > Key: HIVE-4113 > URL: https://issues.apache.org/jira/browse/HIVE-4113 > Project: Hive > Issue Type: Bug > Components: File Formats > Reporter: Gopal V > Assignee: Brock Noland > Fix For: 0.12.0 > > Attachments: HIVE-4113-0.patch, HIVE-4113.patch, HIVE-4113.patch > > > select count(1) loads up every column & every row when used with RCFile. > "select count(1) from store_sales_10_rc" gives > {code} > Job 0: Map: 5 Reduce: 1 Cumulative CPU: 31.73 sec HDFS Read: 234914410 HDFS Write: 8 SUCCESS > {code} > Where as, "select count(ss_sold_date_sk) from store_sales_10_rc;" reads far less > {code} > Job 0: Map: 5 Reduce: 1 Cumulative CPU: 29.75 sec HDFS Read: 28145994 HDFS Write: 8 SUCCESS > {code} > Which is 11% of the data size read by the COUNT(1). > This was tracked down to the following code in RCFile.java > {code} > } else { > // TODO: if no column name is specified e.g, in select count(1) from tt; > // skip all columns, this should be distinguished from the case: > // select * from tt; > for (int i = 0; i < skippedColIDs.length; i++) { > skippedColIDs[i] = false; > } > {code} -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators For more information on JIRA, see: http://www.atlassian.com/software/jira