Question

Is there any way in couchdb to update all documents matching certain conditions? (e.g. create new fields and set values to something based on other data in the document)

I realize that if “new” data can be functionally derived from existing data, then technically you can accomplish this via new views w/o changing the documents, but I need to update a few thousand documents with essentially the same operation.

Answer 1

You can use the bulk docs api:
http://wiki.apache.org/couchdb/HTTP_Bulk_Document_API
but you will need to have all the docs first, and submit them back.

or a doc update handler: http://wiki.apache.org/couchdb/Document_Update_Handlers but you at least need to know a list of doc ids, and do one request per id.

Either way, there is nothing like sql where you can issue an update/where statement.