[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
joins.

http://www.erlang.org/doc/man/qlc.html

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

http://www.pragprog.com/titles/jaerlang/programming-erlang

Kenny

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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