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

Toby Thain <>
Thu Nov 4 23:57:22 CET 2010


On 04/11/10 6:11 PM, Ahmed Omar wrote:
> Hi Joe, All
> I'm far from being a database expert too, so feel free to correct me ,  but
> i believe the assumption of storing simple thing is not a general rule and
> should not be associated with SQL. For example, postgresql provides more
> complex data types and even user defined ones.

As Joe must be aware, it is a tenet of the relational model that column
values be 'atomic' in the sense that they do not encode structure that
would be more profitably decomposed into relations.

--Toby

> 

> 
>> On Tue, Nov 2, 2010 at 9:14 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. ...
>>> * 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?
>>

> On Thu, Nov 4, 2010 at 11:01 PM, Joe Armstrong <> wrote:

>> I'm no database expert so don't quote me here ...
>>
>> As far as I am concerned traditional databases like SQL suffer
>> from the fact that the data stored in an individual column is incredible
>> simple - I can store an integer/string/... in a column but these are
>> incredibly simple data structures. I want to store and retrieve incredibly
>> complicated things - how do I store an XML parse tree in a single cell
>> of a database? - How do I store a database in a database ...
>>...
>> It seems to my that SQL provides you with the ability do to complex
>> queries on simple things. K-V dbs can do simple queries on complex
>> things.
>>
>> /Joe
>>
>>
>>
>>>
>>> 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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>>
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> 
> 



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