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From Chris Anderson <jch...@apache.org>
Subject Re: Restricting user interactions to a single document -- was [VOTE] Apache CouchDB 0.9.0 release
Date Fri, 27 Mar 2009 11:54:45 GMT
On Thu, Mar 26, 2009 at 6:00 PM, Tim Parkin <info@timparkin.co.uk> wrote:
> Antony Blakey wrote:
>>
>> On 26/03/2009, at 6:18 AM, Tim Parkin wrote:
>>
>>> I don't want to have to repeat myself but *it's not about the
>>> consistency or atomicity*. It's about being able to make two or more
>>> changes in a single request (via a UI or API) and if the last one fails,
>>> being able to roll the first ones back and tell the user "Sorry,
>>> something went wrong, would you like to try again" instead of "you have
>>> a partial success, how would you like to deal with it?"
>>
>> In what way is that not atomicity?
>
> Well the difference is I'm more interested the ability to rollback than
> the atomicity. The philosophical objection (AFAICT) is to the atomicity
> of bulk_docs. So if we can simplify the rollback that would be goal
> number 1 acheived..

There is a ticket to allow a database to be rolled back to a specific
sequence id. Of course it can not be rolled to a seq-id that is older
than the last compaction.

https://issues.apache.org/jira/browse/COUCHDB-120

With this implemented, if a user has a node to themselves, they can
always roll back to an earlier state. Replication to a remote master
node would be the equivalent of committing the local transaction. Of
course other users of the remote master will see intermediate as the
replication proceeds, so it's not really a transaction, just the
ability to rollback some actions.

Chris

-- 
Chris Anderson
http://jchrisa.net
http://couch.io

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