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Subject: Re: Frugal Erlang vs Resources Hungry CouchDB
From: Jens Alfke <jens@mooseyard.com>
In-Reply-To: <BANLkTimvDxfTth=m_oZmYJYpKp8KoKh3wg@mail.gmail.com>
Date: Wed, 29 Jun 2011 17:50:03 -0700
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References: <BANLkTimvDxfTth=m_oZmYJYpKp8KoKh3wg@mail.gmail.com>
To: user@couchdb.apache.org


On Jun 29, 2011, at 4:59 PM, Zdravko Gligic wrote:

> In many places I have read how Erlang runs on small devices and how
> (as a result) it is very frugal with resources.  I think that I have
> read that or at least something to that effect.

I=92m not an Erlang expert, but the =93typical=94 use-case Erlang was =
designed for was running Ericsson=92s telecom switches, which are not =
small devices. The resource advantage it has is very lightweight =
parallelism, so you can run tens of thousands of =91processes=92 at once =
without consuming huge amounts of RAM in stack space.

> Whenever I come across such CouchDB resources related postings, I keep
> thinking about all of those Couches on all of those mobile devices (at
> least in all of those presentations and slides) and asking my self
> "how do they do that" ?

A mobile device is typically going to use CouchDB to store =
personal-sized data sets, like your to-do list or phone book or bug =
queue, or your save state in a game. And it=92s probably going to have =
one client at a time, connected by loopback on localhost, sometimes =
making a single sync connection to an upstream server database.

In other words, it=92s not going to be serving a million-document =
corporate database to thousands of clients simultaneously.

For those sort of workloads, CouchDB runs fine on a mobile device, =
especially if the client compacts the database frequently.

SQLite might be a good comparison =97 you could use it to manage very =
large databases [although maybe not so well as MySQL or Postgres] and =
for that purpose you=92ll want a good amount of RAM and disk space. But =
for small data sets, it fits fine into embedded devices like iPhones and =
even microwave ovens.

=97Jens=