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From Wout Mertens <wmert...@cisco.com>
Subject Re: [user] Re: The Blog
Date Mon, 09 Feb 2009 17:10:44 GMT
On Feb 9, 2009, at 4:50 PM, Jan Lehnardt wrote:

> On 9 Feb 2009, at 16:18, Wout Mertens wrote:
>
>> On Feb 9, 2009, at 3:57 PM, Noah Slater wrote:
>>
>>> On Mon, Feb 09, 2009 at 09:51:18AM -0500, Adam Petty wrote:
>>>> Could this thread be added to the wiki - with only minor editing  
>>>> for length
>>>> - maybe as "a RDBMS vs couch 'Discussion' ?"  or something  
>>>> similar?"...
>>>
>>> We've learnt from the book that such comparisons tend to be harmful.
>>>
>>> They lead people into thinking that there is a direct meaningful  
>>> comparison.
>>>
>>> Fundamentally, CouchDB and RDMS solve different problems.
>>
>> I dunno, I think it would be interesting to compare the main  
>> benefits of each so that you know what the strong points of each are.
>
> Quoting myself from a few mails ago:
>
>> CouchDB solves the[sic] similar problems as an RDBMS, but starting
>> from a different angle (distributed operation instead of single-node
>> operation, CAP, yadda yadda).
>
> The differences as a consequence of different CAP-feature priorization
> would be interesting, but then, I had hoped that the "Eventual  
> Consistency"*
> chapter had done that.
>
> * http://books.couchdb.org/relax/eventual-consistency

Funny how nobody is really upset about the schema missing versus  
RDBMS. It seems like schemas are a lot like static typing in  
programming languages - no matter how you look at it, there are a  
*lot* of people doing just fine without it.

I remember taking Databases at university and we had to read this book  
(forgot which one but it's pretty much the standard) and the schema  
and relational concepts are very intertwined. I really liked the  
theory where you would make a fully decomposed DB schema and then used  
queries to tie everything together. The thing I liked best was  
writeable queries, basically if you are careful you can automatically  
update the underlying tables except in some edge cases, thanks to a  
strict schema. However, as far as I know no current RDBMS implements  
this. Maybe there isn't much use for schemas. Non-trivial applications  
can't rely on just schemas for data validation.

A thought occurred: If you are consistent in interfacing with your  
database using only views, then you have created an ad-hoc schema.  
This is probably old news to most of you but it felt nice realizing  
it ;-)

So basically I'm saying maybe schema-free should be touted more as a  
nice-to-have feature?

Wout.


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