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From Paul Davis <paul.joseph.da...@gmail.com>
Subject Re: Documentation: 1. Order in which replication is executed 2. Single invocation multiple ports 3. Replication bound to a
Date Fri, 11 Dec 2009 20:46:04 GMT
On Fri, Dec 11, 2009 at 3:34 PM, Ceriel Jacobs <cerieljacobs@gmail.com> wrote:
> Dear list,
>
> 1. Quote from the documentation: [1]
>> "... for each updated document, only fields and blobs that have changed are replicated...
If replication > fails... the next replication restarts at the same document where it left
off"
>
> My question is: "How is the order of replication?"
> In other words: "In which order are things in a CouchDB replicated?"
>
> For instance:
> * 1st most recent changes, 2nd older changes, 3th oldest changes
> and/or
> * 1st inserts, 2nd updates, 3th deletes
> and/or
> * 1st data, 2nd BLOB's
> and/or
> * 1st documents in the top of the tree, 2nd are documents in the second level of the
tree, etc.
> and/or
> * 1st walking down a tree till its leave, then the next leave of the same parent, until
the last, and then one level up
>
> Any information that clarify the inner workings is welcome.
> Especially in situations with mixed data and BLOB's.
>
> In case BLOB's are replicated with identical priority as stored data, that could lead
to a design decision where BLOB's will not be stored in CouchDB though on the file system
level. This to ensure that textual content is replicated with highest priority.
>

I should've also mentioned that update_seq is the log of most recent
edit for each document. Ie, if you PUT doc1, PUT doc2, DELETE doc1 the
update sequence would look like:

2: doc2
3: doc1

In which case, doc2 would be replicated before doc1.

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