On Fri, Jul 1, 2011 at 15:10, Jens Alfke <[email protected]> wrote:
> A few questions about how attachments interact with document revisions. Since 
> an attachment is conceptually [if not actually] embedded in a revision, you 
> can end up with multiple document revisions that contain attachments with the 
> same name but different contents. That is, attachments are versioned. Right?
>
> 1: I haven’t seen this explicitly stated in the docs, but I assume that you 
> can retrieve an attachment from an earlier revision of a document by doing:
>        GET /db/document_id/attachment_name?rev=revision_id

I think so.

>
> 2: When I GET a document, I just get stubs in the _attachments dictionary. 
> Presumably if I PUT a new revision of the document, leaving the _attachments 
> dictionary the same, the attachments will stay the same in the new revision. 
> And if I remove one of the entries from _attachments, will the corresponding 
> attachment be deleted?

Again, I believe this is the case.

>
> 3: Is there any way to tell whether the attachment in one revision is the 
> same as the attachment in another revision, i.e. whether the attachment 
> changed between the two revisions? Or do you have to compare lengths and, if 
> they’re the same, GET both revisions in their entirety and byte-compare them?
>
> —Jens

The stubs in the _attachments object each have a "revpos" property
that should correspond to the first part of the _rev where they were
last modified. Does that help?

Anyway, from IRC:
<davisp> Jens has questions on the ML that seem like things we should
have in the test suite

So I'm starring these and I'll look into these when I have more time.
If you get to it before I do please file anything you think is an
issue (or file as an improvement) on JIRA.
Thanks!

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