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 79F309DC865; Fri, 30 Dec 2005 09:35:36 -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 56883-10; Fri, 30 Dec 2005 09:35:40 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey- X-Greylist: from auto-whitelisted by SQLgrey- Received: from smtp.nildram.co.uk (smtp.nildram.co.uk [195.112.4.54]) by postgresql.org (Postfix) with ESMTP id 6FDD69DC94D; Fri, 30 Dec 2005 09:35:34 -0400 (AST) Received: from [192.168.0.3] (unknown [84.12.200.250]) by smtp.nildram.co.uk (Postfix) with ESMTP id D143C2687ED; Fri, 30 Dec 2005 13:35:35 +0000 (GMT) Subject: Re: [HACKERS] Online backup vs Continuous backup From: Simon Riggs To: Bruce Momjian Cc: Tom Lane , PostgreSQL-development , PostgreSQL-documentation In-Reply-To: <200512261846.jBQIkcN12733@candle.pha.pa.us> References: <200512261846.jBQIkcN12733@candle.pha.pa.us> Content-Type: text/plain Date: Fri, 30 Dec 2005 13:35:37 +0000 Message-Id: <1135949737.5052.21.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 (2.2.3-2.fc4) Content-Transfer-Encoding: 7bit X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, score=0.03 required=5 tests=[AWL=0.030] X-Spam-Score: 0.03 X-Spam-Level: X-Archive-Number: 200512/37 X-Sequence-Number: 3385 On Mon, 2005-12-26 at 13:46 -0500, Bruce Momjian wrote: > Tom Lane wrote: > > Bruce Momjian writes: > > > I suggest the following patch to rename our capability "Continuous > > > Backup". > > > > This doesn't seem like an improvement. "Online backup" is the standard > > terminology AFAIK. > > But why is it the standard terminology? It doesn't seem logical. Well, as Greg says its a physical backup that can be done on-line, so online backup makes perfect sense to me. I've never had somebody say "that makes no sense" before. Nomenclature is different everywhere, I accept. I generally describe it like this: Logical Backup - use pg_dump - must be done on-line Physical Backup All file copy only - must be Cold/Off-line backup All file copy + WAL archiving - allows Hot/Online or Cold/Offline backup People understand those terms... When do I mention PITR? Well, I describe this as Archive Recovery, with an option to go to end-of-logs, or to a point-in-time. [In the code, the mode variable is InArchiveRecovery.] I do think that saying "do you use PITR?" makes little sense. We should be talking about the backup mode, not the potential future recovery mode. I think it would all make more sense if we described the use of archive_command = something as being in "WAL Archive Mode". That would then allow us to say: "You can only take Online Backups while in WAL Archive Mode". "If you ever wish to perform PITR, you must use WAL Archive Mode". "If you backed-up in WAL Archive Mode, you can perform an Archive Recovery". Best Regards, Simon Riggs