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From Randall Leeds <randall.le...@gmail.com>
Subject Re: Backup, Point In Time recovery
Date Fri, 17 Jun 2011 22:35:29 GMT
On Fri, Jun 17, 2011 at 05:07, Patrick Barnes <mrtrick@gmail.com> wrote:
> I would *really* like to have functionality like this...
>
> Perhaps a mechanism to manage serial snapshots of the db's state?
>
> It seems to me be that maybe a snapshot could just be a header that does not
> get compacted away, and that one could:
>  - 'Roll-back' the database to a given snapshot. (Undo, but not necissarily
> Redo)
>  - Generate, save, or apply a delta between two snapshots.
>  - Clear snapshots when no longer needed, so they are compacted away.
>

It'd require a few changes, but theoretically possible.
We just move from having one valid db header to several headers. It's
a bit like root sets in garbage collection.

> Disclaimer - I may not know what I'm talking about.
>
> -Patrick
>
> On 17/06/2011 4:58 PM, Dave Cottlehuber wrote:
>>
>> On 17 June 2011 14:55, Thomas Hommers<thomas.hommers@ebalu.com>  wrote:
>>>
>>> Hi Nils,
>>>
>>>> CouchDB uses an append-only file format, so you can safely use tools
>>>> like cp or rsync to easily create a point-in-time snapshot of a database.
>>>
>>> That were my thoughts.
>>>
>>> So it will be replication, then filesystem snapshot of the database with
>>> rsync to store different versions to travel back in time if necessary.
>>>
>>> Does anybody has some other idea? Does anybody know how to "cut" the end
>>> of a couchDB file ?
>>>
>>> Regards
>>> Thomas
>>>
>>
>> Hi Thomas,
>>
>> Good approach.
>>
>> Its not clear why you want to cut the end of a DB file but dd or
>> anything like that will do the job. CouchDB will scan back from the
>> end to find the last valid header so an accurate snip is not required.
>>
>> I've considered having a replication endpoint that simply logs
>> _changes to an audit file, something like this would allow you to
>> replay a specific change if required.
>>
>> A+
>> Dave
>>
>

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