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From Alexander Shorin <>
Subject Re: A million databases
Date Tue, 25 Mar 2014 08:47:37 GMT
On Tue, Mar 25, 2014 at 11:41 AM, Suraj Kumar <> wrote:
> I constantly see "one DB per user" being proposed as a solution. But I'm
> not entirely convinced whether this will truly work for a large scale
> setup.
> The reason people choose CouchDB is for high scale use where one could
> potentially end up with a million users. Then, what good is a database  hat
> only relies on the underlying filesystem to do the job of index keeping? If
> there are a million "*.couch" files under var/lib/couchdb/, I'd expect the
> performance to be very poor / unpredictable since it now depends on the
> underlying file system's logic. How can this be partitioned?
> What is the "right" way to handle million users with need for isolated
> documents within each DB? How will replication solutions cope in
> distributing these million databases? 2 million replicating connections
> between two servers doesn't sound right.

This would be fixed with BigCouch merge where information of databases
is stored inside special database.

As for plain CouchDB, you may use / (slash) character in name to group
databases on filesystem layer. Say, you name users databases with some
hash name like: 00007fda . Then you may insert this character in the
middle to produce the next structure:

---- 4ea7.couch
---- 7fda.couch
---- dd47.couch
---- bbc1.couch

and so on. This will reduce negative FS behavior for million files
inside single directory.


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