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From Jan Lehnardt <>
Subject Re: Couch as a mail store?
Date Thu, 12 Feb 2009 14:26:26 GMT

On 12 Feb 2009, at 15:13, Kenneth Kalmer wrote:

> Hi everyone
> This is my first post, please be gentle as I risk ridicule. I've been
> lurking here for several months now, learning from others.  
> Disclaimer, I
> have yet do do more with couch than updating and running the tests.

No worries, we don't bite (...usually :).

> How would couch fair as a backend for a mail delivery system (in  
> concept)?

Two words: Perfect match.

> Considering you need high availability and very fast IO. Documents  
> (email
> messages) will be created and deleted very often, some almost
> instantaneously.
> Couch has some great attributes that makes it sound worth exploring  
> further:
> * Fast lookup of documents
> * Awesome replication for business continuity (especially in a low- 
> latency
> environment like GIG-E)
> * Scales horizontally
> * Ability to pull entire mailbox for user as one result, or at least  
> bundle
> X emails together in one response
> I can't recall seeing any thread on here in recent history  
> discussing high
> document deletion rates, which is effectively the case when people  
> pop their
> mail.

A deletion is effectively a set-deleted-flag operation. Compaction  
then takes
care of getting rid of the file.

> Normal filesystem-based storage of mail has other issues:
> * Messages often smaller than ethernet jumbo frames, so limited  
> throughput
> (couch can overcome this by bundling messages in a single response)
> * Mostly limited by disk IO and clever tricks around solid state  
> drive usage
> or stripping excessively fast disks
> Lets assume nothing about existing mail stores, except that  
> filesystem ones
> don't scale will, and I don't even want to consider the possibility of
> raping an RDBMS for this.
> Everything is exploratory, the thought just crept into my mind a  
> couple of
> days ago and I'd like to bounce the idea around with everyone for fun.
> Thanks for all the hard work, and everyones patience with newbies and
> attackers alike.

Hey, thanks for the nice words :)

Hmm, not too much information. Let's see, if you have any more specific
questions, just send a follow up :)


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