Hi Gary,

I suspect that a lot of the constraints (part, UNIQUE and
PRIMARY KEY) have to be seen as an implementation requirement by
CA for Ingres to meet some particular ANSI Classification. That makes
all the business managers happy. Plus it allows the system to interact
with 3rd parties who may expect to see this style of doing business.

The fact that Ingres has implemented these constraints through
indexes and base table structures from the year dot being of no
importance to the above.

How you decide to implement uniqueness in your system is
upto you - but at least you have options!

If it makes you feel any better....

modify a table with constraints. It cant be done in 2.5. You have
to drop the constraints, modify the table restore the constraints. And of
course if these are referential constraints then you'll have to drop the
constrants from several tables first. Now of course you might be quite
rightly thinking - I'm modifying the table structure not adding or
removing data so why would the system care about constraints at all.
Again there was some problem found in recoverability and so the
modify was switched off. Its resolved in R3 and in 2.6 (I think) and there
are patches to allow an environment variable to be set to allow the
modify.

Guess how I found that out!

And lets just not touch on Constraints vs RFPs.

Martin Bowes.
--
Random Farscape Quote #23:
John - God how I hate God-like aliens, give me a Critter any day.