Return-Path: X-Original-To: apmail-hbase-issues-archive@www.apache.org Delivered-To: apmail-hbase-issues-archive@www.apache.org Received: from mail.apache.org (hermes.apache.org [140.211.11.3]) by minotaur.apache.org (Postfix) with SMTP id 16790FFCB for ; Thu, 21 Mar 2013 05:33:17 +0000 (UTC) Received: (qmail 17786 invoked by uid 500); 21 Mar 2013 05:33:16 -0000 Delivered-To: apmail-hbase-issues-archive@hbase.apache.org Received: (qmail 17756 invoked by uid 500); 21 Mar 2013 05:33:16 -0000 Mailing-List: contact issues-help@hbase.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Delivered-To: mailing list issues@hbase.apache.org Received: (qmail 17727 invoked by uid 99); 21 Mar 2013 05:33:16 -0000 Received: from arcas.apache.org (HELO arcas.apache.org) (140.211.11.28) by apache.org (qpsmtpd/0.29) with ESMTP; Thu, 21 Mar 2013 05:33:16 +0000 Date: Thu, 21 Mar 2013 05:33:16 +0000 (UTC) From: "Lars Hofhansl (JIRA)" To: issues@hbase.apache.org Message-ID: In-Reply-To: References: Subject: [jira] [Updated] (HBASE-8151) Small optimization in HFileReaderV2 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/HBASE-8151?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ] Lars Hofhansl updated HBASE-8151: --------------------------------- Status: Open (was: Patch Available) > Small optimization in HFileReaderV2 > ----------------------------------- > > Key: HBASE-8151 > URL: https://issues.apache.org/jira/browse/HBASE-8151 > Project: HBase > Issue Type: Bug > Reporter: Lars Hofhansl > Attachments: 8151-0.94.txt, 8151-0.96.txt, 8151-0.96-v2.txt, 8151-0.96-v3.txt > > > HFiles V2 store the memstoreTS of each KV. > In many cases all the KVs in an HFile will have a memstoreTS of 0 (that is the case when at the time the HFile was written there are no KVs that were created after the oldest still active scanner - which is frequently the case). > In that case we: > # do not need to decode the memstoreTS (a vlong), since we know its value is 0 and its length is 1 byte. > # when we compact HFiles and all of the involved files have only KVs with memstoreTS = 0 we know ahead of time that all KVs meet this condition and we do not need to store the memstoreTS in the new HFile. > This issue will cover the first part. The performance improvement will be modest as it is fairly cheap to decode vlongs of size 1. -- 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