Return-Path: X-Original-To: apmail-hadoop-mapreduce-dev-archive@minotaur.apache.org Delivered-To: apmail-hadoop-mapreduce-dev-archive@minotaur.apache.org Received: from mail.apache.org (hermes.apache.org [140.211.11.3]) by minotaur.apache.org (Postfix) with SMTP id 3A7899E32 for ; Tue, 3 Apr 2012 15:29:36 +0000 (UTC) Received: (qmail 71191 invoked by uid 500); 3 Apr 2012 15:29:35 -0000 Delivered-To: apmail-hadoop-mapreduce-dev-archive@hadoop.apache.org Received: (qmail 71114 invoked by uid 500); 3 Apr 2012 15:29:35 -0000 Mailing-List: contact mapreduce-dev-help@hadoop.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: mapreduce-dev@hadoop.apache.org Delivered-To: mailing list mapreduce-dev@hadoop.apache.org Received: (qmail 71106 invoked by uid 99); 3 Apr 2012 15:29:35 -0000 Received: from minotaur.apache.org (HELO minotaur.apache.org) (140.211.11.9) by apache.org (qpsmtpd/0.29) with ESMTP; Tue, 03 Apr 2012 15:29:35 +0000 Received: from localhost (HELO mail-lpp01m010-f48.google.com) (127.0.0.1) (smtp-auth username omalley, mechanism plain) by minotaur.apache.org (qpsmtpd/0.29) with ESMTP; Tue, 03 Apr 2012 15:29:35 +0000 Received: by lagu2 with SMTP id u2so6366783lag.35 for ; Tue, 03 Apr 2012 08:29:33 -0700 (PDT) MIME-Version: 1.0 Received: by 10.152.133.68 with SMTP id pa4mr14565494lab.12.1333466973389; Tue, 03 Apr 2012 08:29:33 -0700 (PDT) Received: by 10.112.75.199 with HTTP; Tue, 3 Apr 2012 08:29:33 -0700 (PDT) In-Reply-To: References: Date: Tue, 3 Apr 2012 08:29:33 -0700 Message-ID: Subject: Re: Reduce output is strange From: "Owen O'Malley" To: mapreduce-dev@hadoop.apache.org Content-Type: text/plain; charset=UTF-8 On Tue, Apr 3, 2012 at 8:25 AM, Pedro Costa wrote: > What I want to ask is: > > - how do I read the values from sequence files that are block, or record > compressed, or uncompressed? You use the SequenceFile.Reader class. > - how do I know if the sequence file is block compressed, record > compressed, or uncompressed? You use the SequenceFile.Reader class. > > - how do I know if it's a sequence file or a Textfile? SequenceFile's always have "SEQ" followed by the version in the first 4 bytes. -- Owen