Re: Is relational theory irrelevant?

From: Serge Rielau <srielau_at_ca.eye-bee-m.com>
Date: Tue, 18 Nov 2003 11:14:30 -0500
Message-ID: <bpdge7$pv$1@hanover.torolab.ibm.com>

Joe "Nuke Me Xemu" Foster wrote:

> "Serge Rielau" <srielau_at_ca.eye-bee-m.com> wrote in message <news:bpc4ci$ogk$1_at_hanover.torolab.ibm.com>...
>
>

>>Ragarding c) the realtional model is built for semantic beauty. Semantic
>>beauty does not make for a fast web-experience. Pipelining however does.
>>So a lot of effort is being made to pipeline SQL. Often the rules of the
>>relational model are bent to get there.

>
>
> This is because SQL is so b0rked. Query optimizers' hands are
> tied because most any transformation could change the results.
>
>

>>Example:
>>SELECT * FROM (SELECT sendmail() FROM T) AS X WHERE c1 > 100;
>>How many emails shall be send? Correct (IMHO) would be: As many emails
>>as there are rows in T. In reality many DBMS will push the predicate
>>through to T for the sake of speed, and most customers evidently don't care.

>
>
> Agreed, queries calling functions with side effects is b0rked.
>
>

Interesting. I didn't intend to allege that side-effects are bad. They are a reminder that SQL has to deal with the real world. Just because soemthingis "out of the databses" interest still requires the DBMS to deal with it because it is in the customers interest.

On the general topic of education (and smoking). While ceasing to do a bad thing is a fairly simple thing mentally. Educating someone to actively think a different way (our brains are not wired in relational!) is a lot more "expensive". Given the amount of work there is do do in the space it is simply not possibly to man the projects with properly educated people because teh education woudl be either too epxensive or there are not enough people available who actually can think be made to think relational.
Let me stick with health and education here. But let's talk about healthy food. As long as I require people to cook (write queries) there is a big need to educate them about what food is good (and how it can go bad). Certainly I know neither how to cook nor how to differentiate between good-carbs and bad-carbs. To anable these healthy lifestyle choices one needs to embedd it a lot mor thorough (highschool) at the cost of other education.
Teh same woudl be true for SQL. It woudl be required for each college(!) diploma to have MORE SQL classes, explaining the model a lot deeper. But that increases the length of studies or requires to kick out other stuff (Java, C?).

Cheers
Serge

-- 
Serge Rielau
DB2 SQL Compiler Development
IBM Toronto Lab

Received on Tue Nov 18 2003 - 10:14:30 CST