X-Original-To: pgsql-docs-postgresql.org@localhost.postgresql.org Received: from localhost (av.hub.org [200.46.204.144]) by postgresql.org (Postfix) with ESMTP id 52D559DCA30; Tue, 27 Dec 2005 14:59:49 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) with ESMTP id 71126-06; Tue, 27 Dec 2005 14:59:49 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey- X-Greylist: from auto-whitelisted by SQLgrey- Received: from stark.xeocode.com (stark.xeocode.com [216.58.44.227]) by postgresql.org (Postfix) with ESMTP id 294999DC9C9; Tue, 27 Dec 2005 14:59:46 -0400 (AST) Received: from localhost ([127.0.0.1] helo=stark.xeocode.com) by stark.xeocode.com with smtp (Exim 3.36 #1 (Debian)) id 1ErK2v-0005yW-00; Tue, 27 Dec 2005 13:59:41 -0500 To: Bruce Momjian Cc: PostgreSQL-development , PostgreSQL-documentation Subject: Re: [HACKERS] Online backup vs Continuous backup References: <200512261755.jBQHt5L21116@candle.pha.pa.us> In-Reply-To: <200512261755.jBQHt5L21116@candle.pha.pa.us> From: Greg Stark Organization: The Emacs Conspiracy; member since 1992 Date: 27 Dec 2005 13:59:41 -0500 Message-ID: <87mzim5psy.fsf@stark.xeocode.com> Lines: 25 User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.4 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, score=0.112 required=5 tests=[AWL=0.112] X-Spam-Score: 0.112 X-Spam-Level: X-Archive-Number: 200512/39 X-Sequence-Number: 3387 Bruce Momjian writes: > I noticed that we are using the term "Online Backup" in our > documentation when we are talking about continuous backup and PITR. > > To me, "online backup" is doing a backup while the system is online > (online-backup), and that is accomplished by pg_dump. Well fwiw what pg_dump does isn't even considered a "backup" at all in other systems. It's a "logical export" or something of that sort. It's not considered a "backup" because it's saving something different than the actual physical database. When you restore you get something (hopefully) logically equivalent but still physically different. Hot backups which is what you read "online backup" to mean is pretty closely tied to PITR log archiving backups. One isn't very useful without the other. Specifically, you can have all the archived logs in the world but if you don't have a backup to start from they're useless. And in postgres I gather hot backups aren't very useful if you don't have the transaction logs necessary to fix any torn pages. -- greg