Re: OT: SQL

On May 4, 12:24 pm, Marshall <marshall.spi...@xxxxxxxxx> wrote:
On May 4, 7:25 am, Charlie-Boo <shymath...@xxxxxxxxx> wrote:

The idea of using preexisting files of arbitrary structure
as part of a dbms is so spectacularly bad I am speechless.

Why?

You have an application that works. It has been designed to be as
efficient as you can. Then Codd comes along and says to use his
system to process queries against its data.

He says to copy the data into flat files and pointers to them. I say
to use the original files where they are.

Which is better and why?

1. He forces you to copy the data - keep it twice. I don't.
2. His way will be slower for several reasons:
a. You have designed it based on its particular spec. He has a
general system that doesn't know anything about the peculiarities of
that data.
b. Your system design was created by people with computers. His
system design was created by the computer only - it uses only the
algorithms built into the Codd system.
c. He uses only flat files and pointers to them. You can also use
hierarchical files and files with conditions placed against the data
in them - the examples I gave earlier: a file of all employees who
earn more than their manager, or of all those who do not, or all
emplyees who have a manager.

In all cases, your programmers designed and optimized your system
based on its particular characteristics. You have the advantage of
knowing these peculiarities. Codd's system was designed independent
of your database and doesn't have that knowledge when it runs. He is
wedded to main files plus indexes. You can use anything.

If all men are created equal, then the designers of the original
system have advantahes over Codd who worked independent of your
application and its database design.

C-B

Marshall

.

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