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List:       postgresql-general
Subject:    Re: [HACKERS] [DOCS] Online backup vs Continuous backup
From:       Simon Riggs <simon () 2ndquadrant ! com>
Date:       2005-12-30 13:35:37
Message-ID: 1135949737.5052.21.camel () localhost ! localdomain
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On Mon, 2005-12-26 at 13:46 -0500, Bruce Momjian wrote:
> Tom Lane wrote:
> > Bruce Momjian <pgman@candle.pha.pa.us> 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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