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From Jens Alfke <j...@couchbase.com>
Subject Re: Why are reads from CouchDB so slow? (1.5MB/s or thereabouts)
Date Fri, 23 Mar 2012 17:09:06 GMT

On Mar 23, 2012, at 9:56 AM, Robert Newson wrote:

> One way to avoid this is to
> use one file for documents and another for attachments. If TouchDB is
> effectively doing that, then that explains how you escape the issue.

Yes — TouchDB stores every attachment as a separate file. It’s a very simple content-indexed
store, where the files are named according to their SHA-1 digests. The document metadata*
contains attachment digests. (This then requires that compaction run a mark-sweep phase where
it collects the digests of all available attachments, then deletes attachment files that don’t
appear in that list.)

—Jens

* https://github.com/couchbaselabs/TouchDB-iOS/wiki/Object-Design-And-Schema

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