Re: Storing data and code in a Db with LISP-like interface
Date: Tue, 18 Apr 2006 10:25:20 +0300
Message-ID: <e2247f$1l9$1_at_emma.aioe.org>
> It is admittedly difficult to articulate why navigational structures
> are difficult to use.
They require many loops in the code.
The programmers don't usually analyze the loop invariants and degenerate
cases.
Some optimizers might have troubles with loops.
> Let me try to put it this way: Knowing the
> "quantity of relationships" between the "nouns", most designers will
> come up with pretty much the same relational schema if they go to
> 3rd-normal-form. The differences will usually be minor between
> designers. The same is not true of navigational structures and thus
> there is no consistency. There are too many ways to do the same thing.
> They "work", but it takes a while to get your head around them because
> each has a different flavor and feel, often depending on the needs of a
> given app, whereas relational schemas (ideally) reflect information
> normalization, not usage patterns.
For the same set of dependencies there might be many normalized schemata.
The base relations are not essential.
Only the expressible relations counts.
> Navigational structures are the "Goto's" of attribute structures: they
> "work", but are difficult to follow and inconsistent.
The pointers are the Goto's.
One of the greatest quality of relations is called "symmetric exploitation".
Received on Tue Apr 18 2006 - 09:25:20 CEST