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From: Simon Riggs <[email protected]>
To: Bruce Momjian <[email protected]>
Cc: Tom Lane <[email protected]>
Cc: PostgreSQL-development <[email protected]>
Cc: PostgreSQL-documentation <[email protected]>
Subject: Re: [HACKERS] Online backup vs Continuous backup
Date: Fri, 30 Dec 2005 13:35:37 +0000
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>

On Mon, 2005-12-26 at 13:46 -0500, Bruce Momjian wrote:
> Tom Lane wrote:
> > Bruce Momjian <[email protected]> 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

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