relational for what? [was: Design Principles Behind Smalltalk, Revisited]

Marcel Weiher marcel at
Wed Jan 3 07:08:29 UTC 2007

On Jan 2, 2007, at 11:10 , J J wrote:
>> J J wrote:
>>>> ... I simply believe in the right tool for the right job,
>>> and you can't beat an RDB in it's domain. ...
>> That's something I've never really understood: what is the domain  
>> in which Relational Databases excel?
> Handling large amounts of enterprise data.  If you have never worked  
> in a large company, you probably wont appreciate this.

Well, I have worked in a large-ish enterprise and my experience was  
that moving *away* from the RDB was central to improving performance  
around a hundred- to a thousandfold, with the bigger improvement for  
the project that completely eliminated the RDB.

> But in a large company you have a *lot* of data, and different  
> applications want to see different parts of it.  In an RDBMS this is  
> no problem, you normalize the data and take one of a few strategies  
> to supply it to the different consumers (e.g. views, stored  
> procedures, etc.).

Har har.  Sorry, but I have seen very few actually reusable data models.

>> - Data too large to fit in memory? Well, most uses today may have  
>> been too large to fit in memory 20 years ago, but aren't today. And  
>> even for really big data sets today, networks are much faster than  
>> disk drives, so a distributed database (e.g., a DHT) will be  
>> faster.   Sanity check: Do you think Google uses an RDB for storing  
>> indexes and a cache of the WWW?
> Are you serious with this (data too large to fit into memory)?  And  
> if you use a good RDBMS then you don't have to worry about disk  
> speed or distribution.

You are kidding, right?

> The DBA's can watch how the database is being used and tune this  
> (i.e. partition the data and move it to another CPU, etc., etc.).

To some limited extent, yes.  But they can't work miracles, and  
neither can the DB.  In fact, if you know your access patterns, you  
can (almost) always do better than the DB, simply because there are  
fewer layers between you and the code.

> Oh, but you found one example where someone with a lot of data  
> didn't use a RDB.  I guess we can throw the whole technology sector  
> in the trash.  Sanity check:  google is trying to keep a current  
> snapshot of all websites and run it on commodity hardware.  You  
> could do exactly the same thing with a lot less CPU's using a highly  
> tuned, distributed RDBMS.

That's a big claim, mister.  Care to back it up?


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