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From Nick North <nort...@gmail.com>
Subject Order of document ids vs order of _changes ids
Date Tue, 07 Feb 2012 16:03:06 GMT
I have a question about the order in which documents are committed to the
database, which I hope a knowledgeable dev can help me out with.

The question is (I think): if I create documents, using CouchDb-assigned
document ids, will they appear in the _changes feed in the order that the
ids were assigned? For example, if the id generation algorithm successively
supplies ids aa, bb, cc, will the changes feed contain aa, bb, cc in that
order, or could a document with a later id "overtake" an earlier one in the
process of being committed to the database to yield, say, aa, cc, bb? A
secondary question is: if the order is preserved, can that be relied on in
future CouchDb versions, or is it coincidental and may change one day?

A bit of background might help, and may possibly suggest that I'm not
asking the right question. I have a set of mutually replicating databases
which have a CouchDb id generation algorithm that produces monotonic
increasing globally unique document ids (details
here<https://issues.apache.org/jira/browse/COUCHDB-1373>).
I'd like to be certain that, if document id xx has been replicated from one
database to another, then all documents that are replicated later have
higher ids than xx. It struck me that this might not be the case if
multiple simultaneous document creations are processed concurrently and get
their document ids assigned early in the process - then a small document
with a later id might be processed more quickly than a large one with an
earlier id and get into the database first.

Any insights would be very much appreciated. Many thanks,

Nick

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