Very Computer

Hi,

I would be very pleased to anyone who will have a look
at the problem described bellow and give me an advise:

We have a program P1 working with database D1. We are
to write new program P2 extending functionality of P1
(that in future will be used instead of the old P1)
that should use modified D1. Both the programs are to
work simultaneously on the same data!

We thought that the best solution would be as it follows:
1) to create a new database D2 containing the same data,
2) then change the structure of D2 in the way we need to
   provide additional functionality for P2,
3) then we  have to make both the databases synchronized,
   i.e. if a user using P1 changes something in D1 the D2
   should be correspondently updated. The same should happen
   if a user using P2 updates D2.

The problem that in general D1 and D2 do not have the same
structure. Could please anyone tell me what is the best way
to provide online synchronization for a couple databases having
different structure (but generally containing the same data)?

Many thanks in advance
Igor Grishin

        Two alternatives you should consider are 1) use the same
database, but access it via a view for one of the two
appliations, 2) Depict the new structure using additional
indexes or a lookup table which references the database.

        Having two, or more, databases which duplicate each other
tends to defeat the whole idea behind DBMS.  The lack of
syncronization of data files was one of the major reasons whey
business was willing to adapt DBMS.

--
Jerry Gitomer
Once I learned how to spell DBA, I became one