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From Brian Candler <B.Cand...@pobox.com>
Subject Re: Restricting user interactions to a single document -- was [VOTE] Apache CouchDB 0.9.0 release
Date Sun, 29 Mar 2009 16:56:41 GMT
On Fri, Mar 27, 2009 at 08:36:05PM +0000, Tim Parkin wrote:
> Yes.. but we're not trying to guarantee consistency, just trying to
> prevent inconsistency where possible

In that case, I'm afraid I don't really understand what the goals are. Do
you want to be able to guarantee a rollback, or not? If you don't care about
rollback always being successful, then you can just PUT back the old
documents.

> At the moment bulk docs are guaranteed atomic if the application crashes
> or validation fails (is this right?).. it's only if there is a conflict
> that atomicity has been made unavailable.

By "at the moment" do you mean current 0.9.0 semantics?

As I understand it there are two versions.

- normal _bulk_docs is not atomic. It is no different do just doing a
  series of PUT operations one after the other, but at a lower HTTP
  overhead. Concurrency control will reject an update if the supplied
  _rev differs from the current one.

- _bulk_docs with "all_or_nothing":true *is* atomic. However it doesn't
  perform concurrency control, but instead will add conflicting versions
  of a document (same as if you added them to a different node, and then
  replicated them back to the node in question)

B.

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