Hi All,

I have a stituation here. I am just posting this message because I want to
understand and share with all other the performance issue regarding tables
and indexes.

I am developing an application where performance is the most important
issue.

I have one table called CO = "customer order"
I have one table called CO_ITEM = "the items of the order CO"

I have one table called INV = "invoice"
I have one table called INV_ITEM = "the items of the invoice INV"

Now happens that the difference between CO and INV is just some fields.
Most fields are common for both tables.

Now there is another fact: I need an historic with all changes with CO.

THE SOLUTION I THOUGHT BEST:

1) create a single table INV for both INVs and COs with all the fields.
2) create a single table INV_ITEM for both INV_ITEMs and CO_ITEMs.
3) for the historic question I just thought about adding four fields in
the primary key of both tables (INV and INV_ITEM) .
The three fields are:
a) a date field for the historic : dt
b) a user id : user_id
c) a field to tell me if the record is a INV or a CO
d) a field to tell me if the record is the present situation


I would like to be sure if this is the best approach or, for instance, I
should keep more tables for better performance.
Thanks in advance,
Marcelo Miorelli



________________________________________________________________________
This e-mail has been scanned for all viruses by Star. The
service is powered by MessageLabs. For more information on a proactive
anti-virus service working around the clock, around the globe, visit:
http://www.star.net.uk
________________________________________________________________________