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From CGS <>
Subject Re: same attachment across documents / databases
Date Fri, 28 Oct 2011 11:14:30 GMT
Hi Gregor,

I might be wrong because I am no expert in that field. But from the 
documentation, one can deduce that all the attachments are inserted into 
the document and not pointing toward a physical file (quite logic if you 
consider the main purpose of CouchDB: web-oriented database). As 
replication mechanism is the same for local replication and replication 
over the network (just transferring the content of data from source file 
to the target file), my guess is that your attachment is copied in all 
the physical files for which a replication operation was applied.

However, depending on your project requests, instead of attachment you 
can use a pointer which you can use it in shows (at the user's end). The 
limitations of such a method are imposed by the cross-domain limitations 
(if you use AJAX).

I hope this answer will help you in designing your project and if 
somebody notice any mistake in my answer, please, correct me.


On 10/28/2011 12:32 PM, Gregor Martynus wrote:
> I wonder how couchDB stores document attachments internally. In particular,
> I'd like to know if I replicate a document with attachments from one
> database to another, will the attachments be stored twice internally or will
> the couchDB be smart enough to understand that the attachment does already
> exist and only needs to link to it?
> I hope my question is clear. In my case, each account has an own database
> with its own documents. Now documents can be shared between accounts which
> will be done using replication. But when attachments would get stored
> multiple times although they are exactly the same I fear that it would use
> up too much space and eventually slow down replications etc?

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