[erlang-questions] Conceptual questions on key-value databases for RDBMs users

Kenny Stone <>
Tue Nov 2 21:34:46 CET 2010

qlc is an erlang query interface you can use with mnesia to do things like


Joe Armstrong's book explains qlc with equivalent SQL statements.



On Tue, Nov 2, 2010 at 3:14 PM, Silas Silva <> wrote:

> This is a message I sent to the 
> discussion group.  I thought it might be interesting to send it
> erlang-questions, so here we go...
> Hi all!
> I have used SQL RDBMSs for some time.  I've never used any very advanced
> feature, but I know enough of it to make database applications.
> Nowadays, I decided it would be interesting to learn some NoSQL
> databases concepts.  So I decided to pick up some Erlang and Mnesia, its
> native key-value database.  More than scalability itself, the most
> valuable feature for me is the possibility of replication and
> synchronization between nodes.
> But all pros have cons as companion.  The lack of a relationship model
> is difficult for who is used to RDBMSs.  So, my question is:
> * Is there any guide, tutorial, book, whatever, that tries to introduce
>  NoSQL databases to SQL users?
> * Key-value databases are surprising simple.  I know you solve
>  relationship by denormalizing data.  What data should be normalized?
>  What shouldn't?  How do you update denormalized data?
> Sorry for such simple and general questions.  Things were simple up to
> the moment that I realized that it would be easily solved with a JOIN
> SQL statement.  :-)
> Thank you very much!
> --
> Silas Silva
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