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From Jens Alfke <j...@mooseyard.com>
Subject Consistent version of a view across multiple queries?
Date Fri, 26 Feb 2010 16:27:13 GMT
If an app wants to iterate over a large view, it seems better to page the output by issuing
multiple queries, using the startkey= and limit= parameters. However, this seems to introduce
race conditions if another client is meanwhile altering the database. I might see half of
the documents before the change and half after. For example, I might see a document show up
twice with two different key values.

Is there any way to avoid this inconsistency? In a SQL database I'd use a transaction for
this, to lock out any database updates in between my series of SELECTs. But CouchDB's architecture
doesn't support that.

It seems like what I want is to specify some kind of clock (timestamp / revision #) in my
view queries, so they all run over the exact same view b-tree. This seems straightforward
at the level of the CouchDB file-format, since it's append-only and the previous view b-tree
still exists in the file. But is this exposed in the API at all?

—Jens
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