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Date: Sun, 22 May 2011 09:28:25 +0200
From: Benjamin Eberlei <kontakt@beberlei.de>
To: user@couchdb.apache.org
Subject: Updating documents for a change in application model
Message-ID: <20110522092825.5656f609@benny-pc>
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Hello,

i have searched the net for a while now and haven't found a good resource on how to handle large scale refactorings in the application model with a CouchDB backend.

So far I thought about using one of the following two different approaches:

1. Eventually migrate the data when it comes "into memory" by saving a version field for example. This however does not work for refactorings that change keys in views. Also it leads to lots of IF version then else code in your model that is really ugly to maintain in the long-run.
2. Use _all_docs to iterate over all documents, detect the ones that need changes and do them. This can probably take a while if you have lots of documents and never trigger all_docs during the "normal" application lifetime.

The first approach may sound good at the beginning but i only see very few use-cases for it other than changing names of fields that are not part of a view key.

Can someone maybe share his experience with regard to point 2 or variations of point 2? Additionally, are there solutions for refactoring CouchDB documents I forgot?

greetings,
Benjamin